The Damage Report

Finally light bulb's Tesla tech gives LEDs a worthy rival
— 12:37 AM on November 20, 2014

Ever since I improbably started blogging occasionally about light bulbs, I've been waiting impatiently to get a look at the first product from The Finally Light Bulb Company. This start-up company from Cambridge, Massachusetts has decided to bring a Tesla-era lighting technology into the consumer space.

The tech is known as induction or electrodeless lighting. Induction tech is pretty closely related to fluorescent lighting: a magnetic field excites gases in an enclosed tube. Those gases generate UV light, which strikes the phosphor coating on the tube, causing it to glow. (I'm probably butchering the details, so go here for more info.) Induction lighting has been used for years in industrial and commercial settings, where its reliability and efficiency are appealing, but the fixtures have been much too large for use in the home. The folks at Finally have worked to miniaturize induction lighting radically, so an entire assembly will fit into the space of a conventional A19 light bulb.

Finally calls its miniaturized version of induction lighting "acandescent technology" in an obvious play on "incandescent"—and a tip of the hat to the firm's goal, which is to replicate the warm, welcoming light of an incandescent bulb with very few compromises.

Now, I have almost no specific details about how Finally's implementation of inductive lighting works. All I have is presumably a finished product packaged neatly in retail garb. Heck, I'm not entirely sure why I have this bulb apparently before just about anyone else. Probably they sent me one since I kept bugging them about it.

That said, I suspect Finally may have deployed a couple of important tools in pursuit of their goal. One such tool could be a very fast cycle time. Old-school fluorescents cycle at 60Hz, and I believe CFLs generally run at 2KHz. Some induction lights cycle as quickly as two and a half megahertz. Finally may have chosen a relatively high operating frequency in order to ensure solid, steady illumination. Also, Finally was undoubtedly very particular when selecting the mix of phosphors to use, since those determine the spectrum of light emitted by the bulb.


The yellow-striped Finally bulb next to a Cree 4Flow and a conventional 60W incandescent

Whatever else is going on, there's no question that Finally's miniaturization efforts have succeeded. The payoff is a bulb whose shape closely mimics the teardrop profile of a traditional 60W incandescent.

The rest of the Finally Bulb's specs are competitive with the incumbent LED offerings, as well. It generates 800 lumens of light output using only 14.5W, just a touch above the 13.5W power consumption of Cree's TW-Series LED. The bulb's color temperature is rated at 2700K, the same as other "soft white" bulbs, and its $9.99 list price is in the neighborhood of the best LEDs, even if it is a couple of bucks higher than Finally initially projected. The bulb is EPA rated for 13.7 years of operation at three hours per day, which Finally backs with a 10-year limited warranty.

This bulb can go places some LEDs can't, too. It's rated for use in damp environments like bathrooms (though not in direct contact with water), and it can also be used in enclosed fixtures. For most intents and purposes, the Finally bulb can be used just like an incandescent. There is one place where it falls a bit short: it's not compatible with dimmer switches. Finally has said that future "acandescent" bulbs could be made to work with dimmers, but this first product doesn't go there.

The biggest question, of course, is about the quality of the illumination it produces. Finally makes a big claim about how its bulb reproduces that familiar, warm incandescent glow: "Finally, it is the same." That's a tall order since even the best LEDs don't measure up to the full-spectrum illumination produced by incandescent lights.

The Finally bulb's spec sheet says it has a color rendering index (CRI) of 83. That's short of the perfect 100 produced by incandescent bulbs, but it surpasses the 80 rating of the excellent Cree 60W Soft White LED. (Cree's TW Series claims a CRI of 93.) That said, CRI is an imperfect measure, so I wouldn't get too hung up on those numbers.

When I installed the Finally bulb in a lamp and flipped the switch, I was greeted with a bit of a surprise. The product's packaging says it's "instant on and instant re-start," but that summation misses an important reality. The bulb does light up immediately when you flip the power switch, but it only begins at about 50% of peak brightness. The light then ramps up to full brightness over the course of the next five or six seconds, so quickly that the change in luminance is easy to observe. The ramp up is faster than any CFL I've ever seen, but it doesn't match the immediacy of LEDs or incandescents.

In fact, it's hard to tell for sure, but I suspect the Finally bulb may not reach its absolute peak brightness until several minutes have passed. If I'm right about that, though, the effect is pretty subtle.

Get past that one quirk, and the rest of the story is quite good. As you can probably tell from the picture above, the bulb offers pretty much perfect omnidirectional light distribution, with none of the challenges LEDs sometimes face on this front.

The illumination from the Finally bulb is, as promised, warm and inviting. In my view, it's easily superior to any CFL. Each one of my poor friends and family members who I've accosted for an opinion have agreed with that assessment without reservation. The difference is not hard to see.

Stare at a room lit by this bulb a little longer, and you'll notice something unexpected: the light it produces is noticeably pink in tone. If you've experimented with CFL and LEDs, you may have noticed that not every 2700K light source produces the same mix of colors. Many CFLs tend to be predominantly green, and they can cast a sickly pallor across a living space. LEDs aren't quite so skewed, but they tend to be relatively yellow in tone.

Finally appears to have chosen a phosphor mix that emphasizes red. That's an intriguing aesthetic choice. The rosy pink light from this bulb runs counter to the cooler, flatter, and more antiseptic feel of many CFLs and even LEDs. This emphasis on the red portion of the spectrum makes the Finally bulb more appealing in certain ways. Wood tones appear deeper and more pronounced. Skin tones look healthier, too. I haven't yet combined three of them in the fixture above our kitchen table, but I suspect food presentation will be more pleasing, as well.

That said, the green walls of my bedroom take on more of a gray cast in this light, so it's not perfect. If you compare them side by side, the Finally bulb actually looks somewhat pinker than a 60W incandescent, kind of like GE's original Reveal bulbs with the neodymium coating. Not that there's anything wrong with that. (Happily, this product doesn't make the mistake of providing noticeably less illumination than a regular 60W bulb, either.)

Overall, I'd say the Finally bulb's light quality nearly rivals that of my favorite LED, Cree's 13.5W TW Series. I'm not sure I could say one is clearly superior to the other in every way. I do think the light from the TW Series is probably a little more balanced. If I were installing lamps in a room full of wood paneling, though, I'd pick the Finally bulb for that mission.

All in all, then, this is a spectacular start for an alternative lighting technology that's new to the consumer space—and an auspicious beginning for the young company that produced it. If you're into this stuff, you should grab one and try it out. The bulb is worth seeing in action, and you'll surely get some use out of it.

Unfortunately, I don't yet know where you can purchase one beyond the pre-order form on Finally's website. The firm hasn't yet announced a final availability date for its first product or a list of retailers that will carry it. I expect we'll be hearing more on that front soon.  I may have to snag a few more of these bulbs for myself once they become available.

70 comments — Last by ThatStupidCat at 9:34 PM on 12/08/14

Cree raises its game, lowers prices with 4Flow bulb
— 8:00 AM on October 28, 2014

Since I posted my Friday night topic and then a blog post about LED light bulbs, I've been quietly waiting for another chance to try out something new and interesting on the lighting front. I figured that chance would come with the introduction of the Finally Bulb, but that company's name is proving to be unintentionally uncomfortable. I'm now told they'll have samples ready next month.

Meanwhile, the folks Cree are making news today with the introduction of a new, cheaper consumer LED bulb. The firm's existing 60W replacement bulbs were already my favorites, and this new bulb further refines the formula. Have a look at, yes, our review sample:

As you can see, this puppy is shaped pretty much exactly like an Edison-style A19 light bulb. Cree has eliminated the external heatsink and replaced it with what the firm calls a 4Flow Filament Design. Without the heavy, bulky external heatsink, this LED bulb is shockingly lightweight—under two ounces—and costs quite a bit less to produce. As a result, the price for the 60W-equivalent bulbs is just $8.97, a dollar less than Cree's current 60W-equivalent offering.

Cree plans to offer 4Flow bulbs in 40W- and 60W-equivalent types, with a choice of "soft white" 2700K and "daylight" 5000K color temperatures. The new bulbs will be sold exclusively through The Home Depot, and they will add to Cree's lineup rather than replacing any existing products. Like other Cree LED bulbs, the 4Flow models are instant-on, compatible with dimmers, and rated for ridiculously long lifetimes.

One obvious competitive target for the 4Flow is Philips' nifty heatsink-free SlimStyle LED bulbs. The SlimStyle 60W equivalent sells for $8.97 at The Home Depot, and right now, my local power company is apparently subsidizing these bulbs in a deal that brings their price down to $5.97 in local stores. The SlimStyle offers excellent illumination that's almost indistinguishable from the Cree's. Its only major drawback is a funky, flat shape that may be a little wider than some fixtures will permit. The 4Flow matches the SlimStyle's base price and offers a more conventional shape.

Cree has managed to eliminate the need for a metal heatsink at the base of the bulb by combining several measures. Most obvious is the venting at the top and bottom of the plastic shroud covering the LEDs. Inside, the 4Flow bulb is divided into four chambers by the reflective metal substrates on which the LEDs are mounted. Each chamber contains two LEDs, for a total of eight in each bulb. The heat generated by the LEDs causes air to circulate, and the bulb is then cooled by convection.

Older Cree bulbs have 10 LEDs inside. Cree says it was able to reduce the LED count in the 4Flow thanks to its new Extreme High Power LEDs.

All of the LEDs inside the bulb are situated on the same plane, so the 4Flow retains the filament-like look familiar from Cree's earlier products. One could easily mistake it for an incandescent upon casual inspection. The 4Flow layout, however, eliminates the dark spot at the top of the bulb. Despite this dark area, the older Cree bulbs cast light in all directions pretty effectively, but I suspect some folks will consider the 4Flow an aesthetic improvement.

One downside of the new design is slightly higher power consumption: 11W versus 9.5W for Cree's earlier 60W equivalent. I got the chance to talk with Mike Watson, Cree's VP of Product Strategy, about the 4Flow, and I asked him about the added power draw. He said that the new bulb draws more power in part because of the different thermal process; it's driving the LEDs harder. He pointed out that the energy cost difference between the two bulbs over their lifetimes works out to about $4—$139 versus $135. Cree saw this tradeoff as acceptable so long as it could lower the price of entry without compromising light quality. He also noted that the 40W-equivalent version of the 4Flow has the same 6W power rating as its predecessor.

The 4Flow's open venting could make it susceptible to some problems that other LEDs wouldn't face, including damage from moisture and bugs. Watson told me the 4Flow isn't rated for use in damp settings, although it could go into outdoor fixtures that provide enough protection. As for bugs, Watson pointed out that the 4Flow's mostly indoor usage model should help stave off some problems. He also explained that LEDs do not emit light in the UV spectrum, so they don't tend to attract bugs like incandescents do. That's really interesting and somewhat reassuring, but I'll have to make it through a few Missouri summers with 4Flows in our indoor lamps before I'm entirely persuaded. I figure we're bound to have a cricket or spider fricassee itself on one of those LEDs eventually.

That worry aside, the Cree 4Flow looks to be the most compelling candidate yet to prompt a house-wide conversion from inefficient incandescents or nasty-looking CFLs. The extent to which it mimics the look and feel of a conventional light bulb is unprecedented. Before talking to Watson, I hadn't realized that Cree bulbs could be used in enclosed fixtures, but they can. The 4Flow's packaging warns only against combining LEDs with CFLs or incandescents in the same fixture. That fact opens up a new front at my house. I reckon having that knowledge will cost me some multiple of $8.97.

The one question Watson couldn't answer directly was whether Cree plans to introduce a TrueWhite version of the 4Flow. Thanks to a neodymium coating that reduces the yellow bias in the light produced by LEDs, Cree's TW Series bulbs produce the best color rendering I've seen this side of an incandescent. I'd flip out over an inexpensive TW Series bulb. Of course, Watson couldn't comment on unannounced products. He did say that Cree is committed to having TW Series bulbs available and that if a TrueWhite version of the 4Flow makes sense, "we'll do it." I suppose time will tell.

85 comments — Last by just brew it! at 1:38 AM on 11/18/14

Civ: Beyond Earth with Mantle aims to end multi-GPU microstuttering
— 3:46 PM on October 23, 2014

The next installment in Sid Meier's Civilization series, Civilization: Beyond Earth, comes out tomorrow. The folks at AMD have been working with its developer, Firaxis, to optimize the game for Radeon graphics cards. Most notably, Firaxis and AMD have ported the game to work with AMD"s lightweight Mantle graphics API.

Predictably, AMD and Firaxis report that Mantle lowers the game's CPU overhead, allowing Beyond Earth to play smoother and deliver higher frame rates on many systems. They've even provided a nice bar graph with average FPS showing AMD in the lead, like so:

That's all well and good, I suppose (although *ahem* the R9 290X they used has 8GB of RAM). But average FPS numbers won't tell you about gameplay smoothness or responsiveness. What's more interesting is how AMD and Firaxis have tackled the thorny problem of multi-GPU rendering in Beyond Earth.

Both CrossFire and SLI, the multi-GPU schemes from AMD and Nvidia, handle the vast majority of today's games by divvying up frames between GPUs in interleaved fashion. Frame one goes to GPU one, frame two to GPU two, frame three back to GPU one, and so on. This technique is known as alternate-frame rendering (AFR). AFR does a nice job of dividing the workload between GPUs so that everything scales well for the benchmarks. Both triangle throughput and pixel processing benefit from giving each GPU its own frame.

Unfortunately, AFR doesn't always do as good a job of improving the user experience as it does of improving—or perhaps inflating— average FPS scores. The timing of frames processed on different GPUs can go out of sync, causing a phenomenon known as multi-GPU micro-stuttering. We've chronicled this problem in our initial FCAT article and, most extensively, in our epic Radeon HD 7990 review. AMD has attempted to fix this problem by pacing the delivery of frames to the display, much as Nvidia has done for years with its frame metering tech. But frame pacing is imperfect and, depending on how a game's internal simulation timing works, may lead to perfectly spaced frames that contain out-of-sync visuals.

Making AFR work well is a Hard Problem. It's further complicated by variable display refresh schemes like G-Sync and FreeSync that attempt to paint a new frame on the screen as soon as it's ready. Pacing those frames could be a hot mess.

In a similar vein, virtual reality headsets like the Oculus Rift are extremely sensitive to input lag, the delay between when a user's head turns and when a visual response shows up on the headset's display. If that process takes too long, the user may get vertigo and go all a-chunder. Inserting a rendering scheme like AFR with frame metering into the middle of that feedback loop is a bad proposition. Frame metering intentionally adds latency to some frames in order to smooth out delivery, and AFR itself requires deeper queuing of frames, which also adds latency.

At the end of the day, this collection of problems has conspired to make AFR—and multi-GPU schemes in general—look pretty shaky. AFR is fragile, requires tuning and driver support for each and every game, and doesn't always deliver the experience that its FPS results seem to promise. AMD and Nvidia have worked hard to keep CrossFire and SLI working well for their users, but we at TR only recommend buying multi-GPU solutions when no single GPU is fast enough for your purposes.

Happily, game developers and the GPU companies seem to be considering other approaches to delivering an improved experience with multi-GPU solutions, even if they don't over-inflate FPS averages. Nvidia vaguely hinted at a change of approach during its GeForce GTX 970 and 980 launch when talking about VR Direct, its collection of features aimed at the Oculus Rift and similar devices. Now, AMD and Firaxis have gone one better, throwing out AFR and implementing split-frame rendering (SFR) instead in the Mantle version of Beyond Earth.

AMD provided us with an explanation of their approach that's worth reading in its entirety, so here it is:

With a traditional graphics API, multi-GPU arrays like AMD CrossFire™ are typically utilized with a rendering method called "alternate-frame rendering" (AFR). AFR renders odd frames on the first GPU, and even frames on the second GPU. Parallelizing a game's workload across two GPUs working in tandem has obvious performance benefits.

As AFR requires frames to be rendered in advance, this approach can occasionally suffer from some issues:

·         Large queue depths can reduce the responsiveness of the user's mouse input

·         The game's design might not accommodate a queue sufficient for good mGPU scaling

·         Predicted frames in the queue may not be useful to the current state of the user’s movement or camera

Thankfully, AFR is not the only approach to multi-GPU. Mantle empowers game developers with full control of a multi-GPU array and the ability to create or implement unique mGPU solutions that fit the needs of the game engine. In Civilization: Beyond Earth, Firaxis designed a "split-frame rendering" (SFR) subsystem. SFR divides each frame of a scene into proportional sections, and assigns a rendering slice to each GPU in AMD CrossFire™ configuration. The "master" GPU quickly receives the work of each GPU and composites the final scene for the user to see on his or her monitor.

If you don’t see 70-100% GPU scaling, that is working as intended, according to Firaxis. Civilization: Beyond Earth’s GPU-oriented workloads are not as demanding as other recent PC titles. However, Beyond Earth’s design generates a considerable amount of work in the producer thread. The producer thread tracks API calls from the game and lines them up, through the CPU, for the GPU's consumer thread to do graphics work. This producer thread vs. consumer thread workload balance is what establishes Civilization as a CPU-sensitive title (vs. a GPU-sensitive one).

Because the game emphasizes CPU performance, the rendering workloads may not fully utilize the capacity of a high-end GPU. In essence, there is no work leftover for the second GPU. However, in cases where the GPU workload is high and a frame might take a while to render (affecting user input latency), the decision to use SFR cuts input latency in half, because there is no long AFR queue to work through. The queue is essentially one frame, each GPU handling a half. This will keep the game smooth and responsive, emphasizing playability, vs. raw frame rates.

Let me provide an example. Let's say a frame takes 60 milliseconds to render, and you have an AFR queue depth of two frames. That means the user will experience 120ms of lag between the time they move the map and that movement is reflected on-screen. Firaxis' decision to use SFR halves the queue down to one frame, reducing the input latency to 60ms. And because each GPU is working on half the frame, the queue is reduced by half again to just 30ms.

In this way the game will feel very smooth and responsive, because raw frame-rate scaling was not the goal of this title. Smooth, playable performance was the goal. This is one of the unique approaches to mGPU that AMD has been extolling in the era of Mantle and other similar APIs.

All I can say is: thank goodness. Let's hope we see more of this kind of thing from AMD and major game studios in the coming months and years. Multi-GPU solutions don't have to double their FPS averages in order to achieve smoother animations or improved responsiveness. I'd much rather see a multi-GPU team producing more modest increases that the user can actually feel and experience.

Of course, while we're at it, I'll note that if you measure frame times instead of FPS averages, you can more often capture the true improvement offered by mGPU solutions. AMD has been a little slower than Nvidia to adopt a frame-time-sensitive approach to testing, but it's clearly a better way to quantify the benefits of this sort of work.

Fortunately, AMD and Firaxis have built tools into Beyond Earth to capture frame times. I have been working on other things behind the scenes this week and haven't yet had the time to make use of these tools, but I'm pleased to see them there. You can bet they'll figure prominently into our future GPU articles and reviews.

88 comments — Last by BIF at 12:47 AM on 11/08/14

AMD's CEO transition is a natural next step
— 7:50 PM on October 8, 2014

I just finished listening in to the conference call for financial analysts regarding AMD's CEO transition from Rory Read to Dr. Lisa Su. As usual in cases like this one, the words spoken by Read and Su were carefully chosen and partially scripted ahead of time. As a result, they didn't offer a completely satisfying answer to the questions on everyone's minds about why Read is leaving just a few short years after he took the helm at AMD. Carefully crafted statements from large companies in a time of change rarely satisfy everyone's natural curiosity. One always wonders if there is a larger story behind the official narrative.

Perhaps we'll find out about a profound internal disagreement or dissatisfaction from the board that led to Read's ouster, as happened with Dirk Meyer in 2011.

In this case, though, I think it's entirely possible the reasons behind this change are fairly straightforward. Read said in his opening statement that one of his mandates upon joining AMD was to pick a successor, and he later stated that he hired Dr. Su with that possibility in mind. Read also pointed out that, on his watch, AMD cut operational expenditures by 30%. One doesn't slash a third of the jobs (or something close to it) at a company of AMD's size without alienating quite a few people.

Perhaps Read very intentionally planned to make sweeping changes, to reconstitute AMD's leadership team and structure, and then to step away in a fairly short window.

That's essentially the picture Read painted during his talk, although he's not one to speak in direct, clear language about much of anything. He'd ask you to "reevaluate the binary condition of the wall-mounted switching mechanism" rather than to "turn off the light."

When questioned about the timing of this move, Read briefly spoke in straightforward terms. He said, "The part I'm good at, I've already done," and "Lisa is uniquely positioned for the next phase."

For her part, Dr. Su echoed Read's sentiments about the transition being part of an intentional plan. She also outlined her priorities for AMD going forward, and there wasn't much daylight between those priorities and AMD's strategy under Read. Even the likely changes she outlined—such as an increased emphasis on co-development of products with customers like AMD did with Microsoft and Sony for their game consoles—echo the strategy Read and this team revealed in early 2012. Dr. Su also emphasized that AMD's investments in new x86 and ARM cores, new graphics IP, and SoC integration are "absolutely critical" to the company's future.

Furthermore, under direct questioning, Read and Su both denied this transition was prompted by a disagreement over AMD's long-term strategy. Dr. Su said she and Rory had "really no disagreements on anything" and have been "very aligned."

If the official portrait of this transition is largely accurate, it would be unusual in the context of AMD's last two CEO transitions.

In this case, my natural skepticism is dampened by a nugget I picked up at CES back in January. It wasn't anything I could report, but a well-placed industry source suggested to me that Dr. Su would very likely replace Read as AMD's CEO "within the next six months." Of course, since this is AMD,  the schedule was optimistic, but that prediction proved accurate—and it lends credibility to the notion that this move was in the works for a while.

By practically all accounts, Dr. Su is well-suited by virtue of her experience and ability to lead AMD. If she does well, it seems likely that Rory Read's tenure will be remembered as a time when a corporate turnaround artist installed new leadership and steered the company in a positive new direction.

That turnaround is still very much in progress, though, and the most difficult stages may yet lie ahead. The K12 (ARM) and Zen (x86) cores are still in development and likely will be for another year or more. AMD will struggle to remain relevant in the CPU market until its new cores arrive. Meanwhile, AMD's graphics division has a daunting challenge to face in the form of Nvidia's ultra-efficient Maxwell-based GPUs.

Dr. Su inherits a company with a clear direction and a potentially bright future, but the next 18 to 24 months could be really rough sailing. Here's hoping she—and the rest of AMD—is up to the challenge.

75 comments — Last by sschaem at 5:41 PM on 10/14/14

Here's another reason the GeForce GTX 970 is slower than the GTX 980
— 3:09 PM on October 1, 2014

I was really under the gun when I was trying to finish up my GeForce GTX 970 and 980 review. As a result, I wasn't able to track down the cause of an interesting anomaly in my test results. Have a look at the theoretical peak pixel fill rate of the GTX 970 and 980 reference cards (along with the Asus Strix 970 card we tested) based on the GPU's active ROP count and clock speed:

  Peak pixel
fill rate
(Gpixels/s)
Peak
bilinear
filtering
int8/fp16
(Gtexels/s)
Peak
shader
arithmetic
rate
(tflops)
Peak
rasterization
rate
(Gtris/s)
Memory
bandwidth
(GB/s)
GeForce GTX 970 75 123/123 3.9 4.7 224
Asus Strix GTX 970 80 130/130 4.2 5.0 224
GeForce GTX 980 78 156/156 5.0 4.9 224

On paper, the GTX 970 ought to be nearly as fast on this front as the 980—and the Asus Strix card ought to be a smidgen faster. The 3DMark color fill test we use has evidently been limited by memory bandwidth at times in the past, but that shouldn't be an issue since all three cards in question have the exact same memory config.

Look at what happened, however, when I ran that synthetic fill rate test:

Despite having superior or equal numbers on paper, the Asus Strix 970 couldn't come close to matching the GTX 980's delivered pixel throughput. I promptly raised an eyebrow upon seeing these results, but I didn't have time to investigate the issue any further.

Then, last week, an email hit my inbox from Damien Triolet at Hardware.fr, one of the best GPU reviewers in the business. He offered a clear and concise explanation for these results—and in the process, he politely pointed out why our numbers for GPU fill rates have essentially been wrong for a while. Damien graciously agreed to let me publish his explanation:

For a while, I've thought I should drop you an email about some pixel fillrate numbers you use in the peak rates tables for GPUs. Actually, most people got those numbers wrong as Nvidia is not crystal clear about those kind of details unless you ask very specifically.

The pixel fillrate can be linked to the number of ROPs for some GPUs, but it’s been limited elsewhere for years for many Nvidia GPUs. Basically there are 3 levels that might have a say at what the peak fillrate is :

  • The number of rasterizers
  • The number of SMs
  • The number of ROPs

On both Kepler and Maxwell each SM appears to use a 128-bit datapath to transfer pixels color data to the ROPs. Those appears to be converted from FP32 to the actual pixel format before being transferred to the ROPs. With classic INT8 rendering (32-bit per pixel) it means each SM has a throughput of 4 pixels/clock. With HDR FP16 (64-bit per pixel), each SM has a throughput of 2 pixels/clock.

On Kepler each rasterizer can output up to 8 pixels/clock. With Maxwell, the rate goes up to 16 pixels/clock (at least with the currently released Maxwell GPUs).

So the actual pixels/cycle peak rate when you look at all the limits (rasterizers/SMs/ROPs) would be :

GTX 750 : 16/16/16
GTX 750 Ti  : 16/20/16
GTX 760 : 32/24/32 or 24/24/32 (as there are 2 die configuration options)
GTX 770 : 32/32/32
GTX 780 : 40/48/48 or 32/48/48 (as there are 2 die configuration options)
GTX 780 Ti : 40/60/48
GTX 970 : 64/52/64
GTX 980 : 64/64/64

Extra ROPs are still useful to get better efficiency with MSAA and so. But they don’t participate in the peak pixel fillrate.

That’s in part what explains the significant fillrate delta between the GTX 980 and the GTX 970 (as you measured it in 3DMark Vantage). There is another reason which seem to be that unevenly configured GPCs are less efficient with huge triangles splitting (as it’s usually the case with fillrate tests).

So the GTX 970's peak potential pixel fill rate isn't as high as the GTX 980's, in spite of the fact that they share the same ROP count, because the key limitation resides elsewhere. When Nvidia hobbles the GTX 970 by disabling SMs, the effective pixel fill rate suffers.

That means, among other things, that I need to build a much more complicated spreadsheet for figuring these things out. It also means paying extra for a GTX 980 could be the smart move if you plan to use that graphics card to drive a 4K display—or to use DSR at a 4X factor like we recently explored. That said, the GTX 970 is still exceptionally capable, especially given the clock speed leeway the GM204 GPU appears to offer.

Thanks to Damien for enlightening us—and for solving a puzzle in our results that I hadn't yet had time to investigate.

41 comments — Last by ronch at 10:18 AM on 10/06/14

TR subscribers get Macrium Reflect for 20-40% off
— 9:22 AM on June 11, 2014

We haven't said much about TR subscriptions for a little while, after the rush of the launch, but this little experiment is so far off to an excellent start. You all proved that reader-supported content can work, and you saved our bacon after weak sales in early 2014. We learned some lessons from the initial introductory period, and now we're making additions and changes to the subscription service in response.

One thing that we've wanted to do is add more value for subscribers, so that more of you who are regular readers will find it worth your time to sign up. To that end, we're very happy to announce our first external benefit for TR subscribers: some handsome discounts on software purchased from the Macrium website, including the outstanding Macrium Reflect backup and imaging solution.

Anyone who subscribes for any amount of money at all, down to $1 payment in our pay-what-you-want system, will get a code good for 20% off at Macrium.com. Those folks who beat the average and get a Gold subscription will receive a code for a whopping 40% off, instead.

If you're a TR Silver or Gold subscriber now, your discount code is already waiting for you. Just go to the user control panel and look for it under the "Features" tab. The code should be redeemable throughout the next year.

I'm very pleased to be able to offer a subscriber discount on a product as good as Reflect. I make use of Reflect in Damage Labs constantly thanks to your recommendations. The program writes a bootable WinPE utility onto a thumb drive, and I use it for imaging all of my test systems. I also back up my own PC with Reflect, and it has saved me from an SSD failure with a flawless restore of a weekly image backup. Not only that, but I've received free updates from Macrium for more than a year now without once being held hostage to a required, paid upgrade due to an "incompatibility" with an upgraded version of Windows—unlike *ahem* some imaging companies.

We have more subscriber benefits in the works along these lines, so do yourself a favor and sign up now. You'll also get all of the other subscriber perks, including single-page article views, print templates, comment reply notifications, a subscriber badge, and access to the Smoky Back Room. Beat the average to get triple upvote/downvotes and access to our four-megapixel image galleries, as well.

Finally, remember, if you like what we're doing, you can always add to your subscription amount to support the cause. Thanks!

46 comments — Last by steelcity_ballin at 11:44 AM on 06/15/14

More light bulbs? Yep, more light bulbs
— 10:29 PM on May 13, 2014

The Internet is a strange and wonderful place. A couple of months ago, I posted a Friday night topic on light bulbs that incited a fair amount of discussion. Not long after that, I kid you not, I started receiving press releases and phone calls from the world's light-bulb brands, as if it made perfect sense for a website with the tagline "PC hardware explored" to be writing about LEDs versus CFLs.

This is a dangerous development.

As you may have gathered from my FNT post, I'm more than happy to geek out about lighting technologies. Quite a few of you are, too, apparently. Heck, I can even tie in my off-hours semi-obsession with my day job.

Watch and learn, kids.

After all, 2014 is already shaping up as the Year of the Display in PC hardware, with technologies like 4K and adaptive refresh rates hitting the market for the first time. There's huge overlap between lighting tech and displays. Backlight quality helps determine the temperature and color gamut of an LCD monitor. Beyond that, we're gonna need some serious candlepower (and efficiency) to make high-dynamic-range displays a reality. And one of the most promising display technologies, OLED, may also be the most promising lighting technology on the horizon. The fates of lighting technology and visual computing are deeply intertwined.

Hence, I've spent a silly amount of my free time lately screwing in various sorts of light bulbs for comparison, and here I am in the middle of a work day writing a blog post about it. It's educational, career-development type stuff.

I'm not sure any sane boss would buy that line, which is why it's great to be your own boss.

Anyhow, I've made a few new discoveries in my light bulb vision quest since last time out. Let me bring you up to date.

The Cree TW Series odyssey
First, I think it was one of you people, out there on the Internet, who posted in my Friday night topic and first made me aware of Cree's TW Series bulbs, a follow-up to the excellent LED lights selling across the U.S. at The Home Depot. Whoever you are, you cost me a fair chunk of change on light bulbs.

I was already a big fan of the Crees, which are superb in fixtures and other sorts of indirect lighting, but the stock Cree 60W replacements aren't quite up to replacing incandescents in every case. Above our kitchen table, for instance, in a triple-socket fixture with exposed bulbs, the regular Cree LEDs produce bright but somewhat harsh light. Under that light, the wood in our table and chairs looks kind of yellowy-green, more so than it does in daylight or with incandescents.

Cree cooked up the TW (or True White) Series in an attempt to rectify that shortcoming. The TW Series bulbs are rated for a Color Rendering Index of 93, substantially higher than the CRI rating of 80 for the regular Cree bulb. I'm not quite sure what all voodoo Cree put into the TW Series in order to achieve this improvement, but one component is a neodymium coating on the glass (similar to GE's Reveal bulbs) that filters out a portion of the light spectrum. I believe there may be a different mix of LED colors inside, as well.

There is a tradeoff involved: the TW Series 60W equivalent uses 13.5W to produce 800 lumens of illumination, while the regular Cree bulb requires only 9.5W to do the same. The TW Series bulb also has a somewhat larger base, so it may not fit into certain fixtures as easily as the stock Cree.

Anyhow, I ordered up some TW Series bulbs with a silly amount of anticipation, and I have to say: I was not disappointed.

Although the TW Series has the same 2700K color temperature rating as the regular Cree bulb, the light produced by the TW Series is much better balanced. When I installed the TWs in our kitchen fixture, the wood in our kitchen table regained its deep red and brown tones. No longer did it look sickly and yellow-green.

Under a lampshade, especially, the TW Series is virtually indistinguishable from an incandescent bulb. I look at it periodically and shake my head. Although there's surely more room for improvement, I think LED lighting technology has hit an important high-water mark here. I don't think most folks could tell the difference between this thing and a 60W incandescent in a casual, side-by-side "taste test."

The only downside of note is that the TW Series bulb doesn't appear to be quite as bright as the stock Cree 60W-equivalent, in spite of the matching lumen ratings. The TW Series illuminates as well as a 60W incandescent, but the stock Cree goes above and beyond that. Depending on the situation, you may find that you prefer the brighter but somewhat less balanced light from the regular bulb. For example, I wound up mixing two TW bulbs with one regular one in our kitchen fixture in order to get the right mix of brightness and quality.

I ordered my TW Series bulbs online, since they weren't available in stores locally, but that's since changed, as I learned from, ahem, an official Cree press release mailing. The TW Series is now available at The Home Depot stores across the U.S. The 60W-equivalent TW Series bulb goes for $15.97 a pop—four bucks more than the standard Cree offering. Since you're potentially looking at owning this thing for 10 years or more, I'd say the premium is worth paying.

My order of a six-pack of bulbs left me armed with a mix of regular and TW Series 60W equivalents. I thought I'd maybe use them to replace some of the remaining incandescents in my house, in places where CFLs just wouldn't cut it. Here's what happened instead: I found myself wandering through the house, swapping out a bunch of the CFLs for LEDs. Turns out, at the end of the day, my affinity for light quality trumps any pretensions of being green. For me, the advent of high-quality LED lighting means the death of CFLs, and I couldn't be happier about it.

Rosewill gets into the LED game
We've reviewed several of Rosewill's keyboards, so when I mentioned light bulbs in that Friday night topic, a keen-eyed PR person from Rosewill insisted on sending me some of their new LED bulbs. You can "see if you like ours better than Cree's!" she suggested perkily via email.

Upon reading that statement, I actually sat back in my chair, inhaled, and said to myself, "That is a bold statement."

But hey, the folks at Rosewill have done a nice job with their mechanical keyboards, so who knows?

These LED bulbs are apparently brand-new products that have just become available at Newegg. Rosewill sent me two different models of LED lights to try out, the warm-white 6.5W bulb rated for 560 lumens and the warm-white 8.2W bulb rated for 660 lumens. The firm doesn't provide an incandescent wattage equivalent for these things. Both of them fall somewhere in between the usual output of 40W and 60W incandescents.

My first impression of the Rosewill LEDs was quite positive. As you can see in the picture above, these bulbs have a compact ceramic base that's less bulky than the Cree's, and they're somewhat shorter in terms of total height, too—very much the size and shape of a traditional incandescent light bulb.

Rosewill rates its soft-white products at a color temperature of 3000K, slightly cooler than the 2700K rating for most soft-white bulbs. In theory, at least, I like the idea of a slightly cooler everyday bulb. So many of the 2700K CFLs I've been using for years at 2700K are too yellowy and seem "off." (There's also a 5000K "cool white" version of each bulb, but I told them not to bother sending those. Ugh. I don't need a grow lamp.)

After screwing the Rosewill 8.2W LED into a lamp and firing it up, I decided maybe 3000K wasn't a great idea. Perhaps this is emitted spectrum instead of just color temperature, but my first thought was that the Rosewill soft-white bulbs emit light that's just a little too Walmart-esque for my tastes. Too much blue to the hue, in my view.

Sorry about that.

I will say Rosewill has one-upped Cree on another front, though. The light produced by this bulb is distributed evenly in a broad, nearly spherical area limited only by the presence of that ceramic base. There aren't any obvious hotspots or dark areas. The Cree's LED tower is more compact and more closely resembles an incandescent filament, but it doesn't emit as much light straight up.

I was torn on whether the Rosewill lights really produced better illumination quality than a CFL when I first tested them in several shaded lamps. The bluish light seemed pretty similar overall. Any doubts on that front were squelched when I subbed in the Rosewill 8.2W bulbs for 13W CFLs in a couple of those three-light open fixtures. The Rosewills performed surprisingly well in direct lighting situations, producing brighter and subjectively higher-quality light than the CFLs they replaced. I also found that the 6.5W bulbs were a nice upgrade in lumen output from a 40W incandescent.

Still, the light quality doesn't really come close to Cree's regular offerings, let alone the TW Series.

The biggest drawback to the Rosewill LEDs, though, is probably the delay on start-up. Like most LEDs, these bulbs reach peak brightness pretty much as soon as they ignite. Trouble is, there's a pretty pronounced delay of a half-second or so (it seems to vary) between flipping the switch and ignition. Seriously, that is a long time. Even CFLs, which take several minutes to reach peak brightness, start producing some light almost instantly. The Crees LEDs are nearly instant-on, too. You can decide how annoying you find this quirk, but personally, I want a faster response when I flip the light switch.

Add in the fact that the Rosewill LEDs aren't compatible with dimmers and only come with a two-year warranty (versus Cree's decade-long pledge,) and it's clear this isn't quite the same caliber of product. That means the Rosewill bulb needs to be cheaper than the Cree, and right now, the 8.2W version is selling for $12.45 at Newegg. This thing needs to cost less, not more, than the market leader.

I suspect Rosewill knows that, and I suspect they'll run discounts and promotions that effectively drop the price of these bulbs over time. At a bit of a discount, these Rosewill bulbs could be a nice value, particularly for use in fixtures where their compact bases, conventional height, and well-distributed illumination would be appreciated.

A new contender emerges
LEDs are getting to be mighty good, but they're not the only lighting technology vying for a spot in sockets after the incandescent ban. The folks at a new start-up company have refined and miniaturized a form of induction lighting in order to create the Finally Bulb, whose story was told at length in this New York Times write-up.

Induction lighting has been used in commercial settings for ages, apparently, but was too large to be practical elsewhere. Finally calls its version of induction tech "Acandescent" lighting, which isn't bad as marketing names go.

The Finally Bulb is set for release this summer, and it looks to be almost exactly the same size as a 60W incandescent. The rest of the specs look pretty decent, too. It requires 14.5W and produces 800 lumens, and the company claims the bulb turns on instantly, with a rated life of 15,000 hours and a warranty spanning 10 years.

Two things could possibly set this bulb apart. One is light quality. The 2700K bulb has a CRI rating of 83, which is higher than the standard Cree LED's rating. The Finally marketing materials focus quite a bit on light quality, claiming this is "the first bulb to truly replicate the look, reassuring warmth and omnidirectional light of the incandescent bulbs you love."

That's a strong claim for a bulb with an 83 CRI. Still, CRI is an imperfect measure, so I'm eager to have a look at one of these things in operation as soon as possible.

The other big deal with the Finally Bulb is its projected price of about $8. That's cheap. If this bulb produces truly appealing light, meets its specs, and undercuts quality LEDs by a few bucks per bucks per socket, it might become yet another a viable alternative option.

99 comments — Last by slate0 at 6:46 PM on 06/11/14