AMD’s Radeon HD 7770 GHz Edition
Can you believe it’s been over two years since we saw a genuinely new mid-range graphics processor from AMD? Oh, sure, the Radeon HD 6770 and 6750 that came out last April had new video decoding logic and HDMI 1.4a support. But other than that, they were pretty much identical to the Radeon HD 5770 and 5750 from the Fall 2009 catalog, down to the Juniper GPUs under their heatsinks.
It’s hard to blame AMD for the lack of progress. When TSMC decided to cancel its 32-nm fab process a few years back, both AMD and Nvidia were left with no choice but to make do at 40 nm until the next process node in TSMC’s roadmap became available. What little new silicon AMD and Nvidia produced was reserved for higher price brackets, and other products just stuck around, getting price cuts and minor facelifts along the way.
The Radeon HD 5770 cost $159 when it came out in October of ’09. Today, you can nab the same card (and its post-facelift alter ego, the Radeon HD 6770) for as little as $100. That combination of longevity, low price, and solid performance has made this card something of a staple for gamers on a budget. According to the Steam hardware survey, the 5770 is the second-most popular choice for Steam users behind Nvidia’s GeForce 9800 series.
In the wake of Valentine’s Day 2012, though, the Radeon HD 5770 (and the Juniper chip within) finally reaches the end of its run. At the stroke of midnight tonight, AMD launches the Radeon HD 7700 series, a new mid-range product line featuring 28-nm silicon, AMD’s latest and greatest GPU architecture, and purported performance improvements. Can the 7700 series live up to so many months of pent-up desire for new mid-range goodness? That’s what we’re here to find out.
Wikipedia says Cape Verde (rhymes with bird) is a republic that spans a small archipelago in the central Atlantic, about 350 miles off the African coast. What does that have to do with graphics processors, you ask? Absolutely nothing. But it so happens that AMD chose Cape Verde as the code-name for its latest GPU, which is featured in the Radeon HD 7700 series. Cape Verde is, fittingly, part of the Southern Islands GPU family that includes Tahiti and the soon-to-follow Pitcairn.
At 123 mm², Cape Verde isn’t very big. It’s actually even smaller than the Radeon HD 5770’s Juniper chip, whose footprint was around 166 mm². Thanks to TSMC’s 28-nm process technology, however, Cape Verde manages to pack a whopping 1.5 billion transistors inside its diminutive die—that’s a 44% increase over Juniper’s 1.04 billion transistors.
There’s much more to Cape Verde than a higher transistor count, of course. AMD has endowed this tiny slab of silicon with its Graphics Core Next architecture, giving it all of the same features as AMD’s new flagship GPU, the Radeon HD 7970. Those features include PCI Express 3.0 compatibility, DirectX 11.1 support, a hardware video encoder block (VCE), improved power management, and last but certainly not least, a revamped shader architecture that’s more efficient and should perform better under general-purpose workloads (think OpenCL and the like).
We could devote entire pages to detailing those features. In fact, we already did, which is why I’m going to spare my fingers and point you to the relevant section of our Tahiti review. Cape Verde and Tahiti share the same architectural DNA, a fact AMD emphasized time and again when it spoke to us last week.
As you might expect, AMD dusted off the world’s smallest chainsaw in order to make Cape Verde suitably small and cheap to manufacture. Take a look at the block diagram below, which provides an abstracted, top-down view of Cape Verde’s various odds and ends:
Now compare that with Tahiti’s block diagram, which we posted here. Cape Verde has only 10 compute units (down from 32 in Tahiti), two 64-bit memory controllers (down from six), four ROP partitions (down from eight), and one geometry engine (down from two). Since the two chips are based on the same core graphics architecture, however, Cape Verde’s compute units each contain the same number of 16-wide vector units (four) and texture units (also four). Cape Verde also has four color and 16 Z/stencil ROP units inside each ROP partition—again, just like Tahiti.
Here’s how Cape Verde stacks up once you do the math:
|Cape Verde||16||40/20||640||1||128||1500||123||28 nm|
Depending on what part of the GPU you look at, Cape Verde has roughly one half to roughly one third the execution resources of Tahiti. It’s also outfitted a little differently than Juniper, with more texture filtering resources but fewer ALUs. I should note that Juniper is based on AMD’s older and less efficient VLIW5 architecture, however, so the figures above don’t tell the whole story.
Anyway, that’s Cape Verde for you: a new chip, a new architecture, and the promise of a breath of fresh air for cash-strapped gamers looking to upgrade. AMD isn’t just launching a new GPU by itself, of course. Cape Verde is making its entrance astride two graphics boards, the Radeon HD 7770 GHz Edition and the Radeon HD 7750. Before we lose ourselves in the fervor of game benchmarking, we should take a moment to introduce these cards.
In its pure, unhindered form, Cape Verde can be found atop the Radeon HD 7770 GHz Edition. Well, atop the board itself, but under that deceptively large red-and-black cooling shroud and the tiny heatsink it conceals.
What you see above is the card AMD sent us. The company was squeamish about us taking pictures of it, because the sample doesn’t have a shiny “GHz Edition” sticker on its cooling fan. Here’s the picture AMD wanted us to show, instead:
Yes, AMD is making quite a fuss over that “GHz Edition” moniker. We’re not entirely sure why. The obvious reason is that the Radeon HD 7770 has a core clock speed of exactly one gigahertz, which leads AMD to tout it as the “the world’s first GPU at 1GHz.” But, see, that’s not strictly true. Other cards have shipped with 1GHz core clocks in the past, and every Nvidia GPU since the GeForce 8800 series has run its shaders higher than the core speed. For several years now, most higher-end GeForces have run their shaders in the 1.5-2GHz range.
All of that is somewhat moot, though, because with any highly parallel processor—and especially with a GPU—clock speed is a very poor predictor of performance.
All you really need to know is that the “GHz Edition” label doesn’t denote a particular variant of the Radeon HD 7770. All 7770s have a base clock of at least 1GHz, and some of AMD’s board partners are offering even quicker variants. (More on that in a second.) The 7770 also features 1GB of GDDR5 memory pushing bits at 4500 MT/s. It draws 100W at most and 80W under typical gaming workloads, requires a lone six-pin PCIe power connector, and has a suggested e-tail price of $159.
Here’s one of those faster variants we talked about: XFX’s Radeon HD 7770 Black Edition. This bad boy runs at 1.12GHz, and its memory pushes an eye-popping 5200 MT/s. Its asking price is equally eye-popping: $179. That kind of money will buy you a nice Radeon HD 6870 nowadays, if you don’t mind the larger power envelope, so this thing had better deliver.
At the other end of the spectrum lies the Radeon HD 7750, whose Cape Verde chip has had two of its compute units disabled. Since each compute unit has four texture units and four 16-wide vector units, the 7750 ends up with 512 shader ALUs and 32 texture units (down from 640 and 32, respectively, on the Radeon HD 7770). The 7750 is decidedly not a GHz Edition; it has a core clock speed of only 800MHz. However, its memory runs at the same speed as the 7770’s, and both cards have the same 128-bit path to memory. Both offerings can also drive six monitors in an Eyefinity configuration, with the use of a DisplayPort hub… and provided you can find one of those.
The 7750’s small sacrifices pay dividends in big ways. With a 75W max power envelope and 55W typical power draw, the card doesn’t need a PCIe power connector, and it can get by with either a single-slot active cooler or a dual-slot passive one. (We’re told Sapphire offers a passively cooled variant.) The 7750 is also, as you’d expect, quite a bit cheaper than its bigger brother, with a suggested e-tail price of only $109.
Ready to move on to the benchmarks? Not so fast. We have a big, meaty table full of peak theoretical numbers for you to pore over first:
| Peak bilinear
| Peak shader
|GeForce GTS 450||783||13||25/25||0.6||3608||58|
|GeForce GTS 450 AMP!||875||14||28/28||0.7||4000||64|
|GeForce GTX 550 Ti||900||22||29/29||0.7||4104||98|
|GeForce GTX 550 Ti Cyclone||950||23||30/30||0.7||4306||103|
|GeForce GTX 460 1GB||675||22||38/38||0.9||3600||115|
|GeForce GTX 560||822||26||46/46||1.2||4008||128|
|Radeon HD 5770||850||14||34/17||1.4||4800||77|
|Radeon HD 5770 Super OC||900||14||36/18||1.4||4800||77|
|Radeon HD 6790||840||13||34/17||1.3||4200||134|
|Radeon HD 6850||775||25||37/19||1.5||4000||128|
|Radeon HD 6870||900||29||50/25||2.0||4200||134|
|Radeon HD 7750||800||13||26/13||0.8||4500||72|
|Radeon HD 7770||1000||16||40/20||1.3||4500||72|
|Radeon HD 7770 Black Edition||1120||18||45/22||1.3||5200||83|
|Radeon HD 7950||800||26||90/45||2.9||5000||240|
|Radeon HD 7970||925||30||118/59||3.8||5500||264|
Judging by these theoretical figures, the Radeon HD 7770 has quite a bit more texture filtering power than the 5770. In fact, its filtering rates are close to those of the Radeon HD 6850. The 6850 does have somewhat higher peak shader performance, but Cape Verde’s Graphics Core Next architecture should do a better job of living up to theoretical peaks than the 6850’s VLIW5 design. It’ll be interesting to see how close the 7770 ends up to the 6850 in real games.
To keep up with the 6850, the 7770 will have to overcome one serious handicap: its limited memory bandwidth. Not only does the 7700 have half the memory interface width of the 6850, but its memory speed is also lower than the 5770’s. That leaves it with a comparatively paltry 72GB/s of bandwidth.
On the Nvidia front, the 7770 will have to contend with the GeForce GTX 550 Ti and the GTX 460 1GB. Making a prediction there is trickier. Both Nvidia cards have higher fill rates and more memory bandwidth, but they’re both more limited when it comes to peak shader arithmetic. The 7700 has higher integer texture filtering performance, but the Nvidia cards can do FP16 filtering at the same speed, something the Radeon can’t do.
Our testing methods
Note that the GeForce GTS 450, GeForce GTX 550 Ti, and Radeon HD 5770 cards we tested all have above-reference clock speeds. We would have loved to test reference-clocked variants, but these were the cards we had on hand when the Cape Verde samples came in the mail. It’s not the end of the world, but you’ll want to keep in mind that other GTS 450, GTX 550 Ti, and 5770 cards you find in stores may be a little slower.
As ever, we did our best to deliver clean benchmark numbers. Tests were run at least three times, and we’ve reported the median result. Our test systems were configured like so:
|Processor||Intel Core i5-750|
|North bridge||Intel P55 Express|
|Memory size||4GB (2 DIMMs)|
|Memory type||Kingston HyperX KHX2133C9AD3X2K2/4GX
DDR3 SDRAM at 1333MHz
|Memory timings||9-9-9-24 1T|
|Chipset drivers||INF update 126.96.36.1995
Rapid Storage Technology 10.1.0.1008
|Audio||Integrated Via VT1828S
with 188.8.131.5200 drivers
|Graphics||Gigabyte Radeon HD 5770 Super OC 1GB
with Catalyst 11.2 preview drivers
|XFX Radeon HD 6850 1GB
with Catalyst 11.2 preview drivers
|Radeon HD 7750 1GB
with Catalyst 8.932.2 drivers
|Radeon HD 7770 1GB
with Catalyst 8.932.2 drivers
|XFX Radeon HD 7770 1GB Black Edition
with Catalyst 8.932.2 drivers
|Zotac GeForce GTS 450 1GB AMP! Edition
with GeForce 295.51 beta drivers
|MSI GeForce GTX 550 Ti Cyclone II 1GB
with GeForce 295.51 beta drivers
|Zotac GeForce GTX 460 1GB
with GeForce 295.51 beta drivers
|Hard drive||Western Digital Caviar Black 1TB
Samsung Spinpoint F1 HD103UJ 1TB SATA
|Power supply||Corsair HX750W 750W|
|OS||Windows 7 Ultimate x64 Edition
Service Pack 1
Thanks to Intel, Asus, Corsair, Kingston, and Western Digital for helping to outfit our test rigs with some of the finest hardware available. AMD, Nvidia, and the makers of the various products supplied the graphics cards for testing, as well.
Unless otherwise specified, image quality settings for the graphics cards were left at the control panel defaults. Vertical refresh sync (vsync) was disabled for all tests.
We used the following test applications:
- Batman: Arkham City
- Battlefield 3
- Deus Ex: Human Revolution
- The Elder Scrolls V: Skyrim
- Fraps 3.4.7
- GPU-Z 0.5.8
Some further notes on our methods:
We used the Fraps utility to record frame rates while playing a 90-second sequence from the game. Although capturing frame rates while playing isn’t precisely repeatable, we tried to make each run as similar as possible to all of the others. We tested each Fraps sequence five times per video card in order to counteract any variability. We’ve included frame-by-frame results from Fraps for each game, and in those plots, you’re seeing the results from a single, representative pass through the test sequence.
We measured total system power consumption at the wall socket using a P3 Kill A Watt digital power meter. The monitor was plugged into a separate outlet, so its power draw was not part of our measurement. The cards were plugged into a motherboard on an open test bench.
The idle measurements were taken at the Windows desktop with the Aero theme enabled. The cards were tested under load running Skyrim at its High quality preset.
We measured noise levels on our test system, sitting on an open test bench, using a TES-52 digital sound level meter. The meter was held approximately 8″ from the test system at a height even with the top of the video card.
You can think of these noise level measurements much like our system power consumption tests, because the entire systems’ noise levels were measured. Of course, noise levels will vary greatly in the real world along with the acoustic properties of the PC enclosure used, whether the enclosure provides adequate cooling to avoid a card’s highest fan speeds, placement of the enclosure in the room, and a whole range of other variables. These results should give a reasonably good picture of comparative fan noise, though.
We used GPU-Z to log GPU temperatures during our load testing.
The tests and methods we employ are generally publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.
Batman: Arkham City
To warm up the new Radeons, we grappled and glided our way around Gotham, occasionally touching down to mingle with the inhabitants.
Arkham City‘s DX11 eye candy is a little too demanding for cards like the Radeon HD 7700 series, so we tested at 1080p in DirectX 9 mode.
Apologies for the hard-to-read line graphs. The simple truth is that most of these cards are neck-and-neck, and all of them exhibit wanton frame latency spikes, making their individual plots hard to distinguish from one another. Let’s dress up the data into something a little more presentable, shall we?
Our average FPS chart also shows most of the cards mashed together, with average performance in the same ballpark.
Thanks to our new benchmarking methodology, we can look inside the second for more subtle differences between these solutions. Our next two charts highlight those differences. The first one shows the latency threshold below which 99% of frames are rendered…
…while the second one tells us how long each card spends working on frames that take longer than 50 ms to render:
Based on these results, the Radeons clearly suffer from fewer abnormal frame latency spikes than the GeForces, with most of their frames rendered under a lower threshold. The differences aren’t huge by any means, but the Radeons are a teeny bit more fluid overall.
Put it all together, and we can confidently say the Radeon HD 6850 and 7770 are the best performers here. Which one is better? Well, it’d be a toss-up if the 6850 weren’t so much cheaper. Newegg’s cheapest 6850 sells for just $139.99 right now, and that’s before a $10 mail-in rebate. The 7770 should consume less power (we’ll test power, noise, and temperatures in a bit), but that may not justify its $20-30 price premium for most folks.
We should say a few words about the Radeon HD 7750, too. This little card actually does slightly better than the competition—our superclocked Radeon HD 5770 and GeForce GTS 450—and at $109, it’s no more expensive. Not bad at all.
We tested Battlefield 3 by playing through the start of the Kaffarov mission, right after the player lands. Our 90-second runs involved walking through the woods and getting into a firefight with a group of hostiles, who fired and lobbed grenades at us.
To keep things playable even on the slowest cards, we used the game’s medium detail preset. We had no qualms about keeping the resolution at 1080p, though. AMD claims even the Radeon HD 7750 can maintain playable frame rates in the latest games at that resolution.
Most of the plots are nestled around the 20-ms frame time threshold, just like they were in Arkham City. This time, however, we recorded substantial quantities of latency spikes on all three Nvidia GPUs. The spikes tended to be quickly followed by short dips well below the average.
The 99th percentile and 50-ms results put the Nvidia cards at a disadvantage, as expected, although the GeForce GTX 460 1GB doesn’t do too badly overall. Still, AMD’s Radeon HD 7770 and 6850 come out on top once again—which really means the 6850 comes out on top, because it’s cheaper and a better performer than the 7770.
Yes, XFX’s Radeon HD 7770 Black Edition technically trounces the 6850, and that’s a commendable feat for a card with half the memory bandwidth of its rival. The 7770 Black also happens to cost $179, though, which makes it more expensive than not just the 6850, but quite a few Radeon HD 6870 variants, as well.
As for the Radeon HD 7750, it falls behind our superclocked 5770 by a substantial margin. A stock-clocked Radeon HD 5770 would probably be quicker than the 7750, too—and cheaper.
Deus Ex: Human Revolution
Here, we played through the beginning of the game’s first real mission (at the Sarif Manufacturing plant) using a mix of stealthy sneaking and gunplay. Human Revolution allows for and rewards both approaches.
Since this game isn’t terribly demanding, we maxed out detail settings and cranked up FXAA antialiasing to “High” at 1080p.
Looks like a repeat of Battlefield 3 results. The AMD solutions are clustered together, and the Nvidia cards suffer from entirely too many latency spikes.
It’s like déjà vu all over again. The Radeon HD 6850 and 7770 rise to the top overall, the 7750 fails to catch up to the 5770 (though, to be fair, it does come closer than in Battlefield 3), and the Nvidia solutions are at a disadvantage because of their numerous frame latency spikes.
The Elder Scrolls V: Skyrim
Our Skyrim run involved running around the town of Whiterun, starting from the city gates, all the way up to Dragonsreach, and then back down again.
Skyrim behaved surprisingly well at 1080p with the “High” preset, so we felt comfortable using that setting across the board. Note that we ran the game with the high-resolution texture patch installed.
There’s something funky going on here. The 7700-series cards exhibit considerably more variance than the rest, with lots of spikes and dips in rapid succession through much of the test. That variance was clearly noticeable when we tested—the game felt like it was skipping along instead of flowing smoothly. We saw something similar with the GeForce GTS 450, but to a much lesser degree.
The 99th-percentile results confirm our observations. The Radeon HD 7770 and 7750 have the highest latency thresholds of the pack. Most of their frame-time spikes lie below 50 ms, however, so they’re not penalized in our “time spent beyond 50 ms” rankings. We can’t say the same for the GeForces, whose more consistent overall frame times were marred by higher occasional peaks.
Now that we know how the new Radeons perform, let’s see how the 28-nm Cape Verde GPU stacks up against the competition in terms of power efficiency. Power consumption influences GPU temperatures and noise levels, too, which we’ll also be looking at.
Like Tahiti, Cape Verde gates off voltage to most of the GPU when the display goes to sleep. AMD calls that feature ZeroCore, and you can see its effects here. Idle power consumption for the whole system drops by exactly 10W when the display shuts off. (According to AMD, the 7770 and 7750 both draw around 3W of power in ZeroCore sleep mode.)
The new Radeons are also the most power-efficient of the bunch under load. Even XFX’s Radeon HD 7770 Black Edition sips power despite its high core and memory speeds, which are well above reference.
If saving polar bears is your game, Cape Verde is the GPU for you.
Noise levels and GPU temperatures
With the exception of the GeForce GTX 460 (and the Radeon HD 6850 under load), none of these cards are terribly loud. The Radeon HD 7750 does have an annoying hiss to it, though, no doubt because of its small fan and single-slot heatsink. I would hope most of AMD’s card partners choose either beefier active coolers or passive heatsinks.
In any case, I believe we’ve located the Radeon HD 7770’s only tangible advantage over the cheaper 6850 right now: its quiet cooler. AMD did a good job tuning the stock cooler for low noise, which probably wasn’t too hard considering the card’s spartan power consumption. You might find 6850 cards on the market with less noisy coolers than our sample, but that’s not a guarantee by any means.
The 7770 runs cool and quiet with the stock heatsink and fan. Nice. The 7750 isn’t doing terribly well with that tiny single-slot cooler, though. We tested on an open test bench, but I wouldn’t want to stick this card in a cramped enclosure with the adjacent expansion slot occupied. And I can just see that tiny, whiny little fan failing after six months.
Let’s round things out with a couple of our famous scatter plots. We’re laying average performance (based on the results from the four games we tested) along the Y axis and prices along the X axis. The sweet spot will be the card closest to the top left of the plot, while the worst will be closer to the bottom right.
We fetched prices for the new Radeons from AMD and XFX, and other prices were gleaned from Newegg. The exact GeForce GTS 450 and Radeon HD 5770 models we tested weren’t listed anymore, so we’ve used prices for slightly slower variants that are still available. That may not be entirely rigorous, but the differences don’t amount to very much.
Well, this confirms what we’ve been saying all along: the Radeon HD 6850 is the way to go in this price range, at least if you’re chiefly concerned about performance per dollar. As we noted on the previous page, the 6850 does have higher power consumption, and depending on which model you get, it may also have higher noise levels.
The Radeon HD 7750 isn’t as much of a lost cause as its faster sibling. In fact, considering how close it ends up to the Radeon HD 5770, I’d be inclined to recommend it—with the caveat that only solutions with third-party coolers should be considered. (The single-slot stock cooler really sucks. No pun intended.) Based on the photos in AMD’s presentation, the 7750 variants from at least Asus, Gigabyte, HIS, MSI, and Sapphire should have dual-slot coolers. Sapphire has a passively cooled model, too.
Before we render our final verdict, let’s get a little wild and compile a value scatter plot out of our 99th percentile frame time data. For consistency’s sake, we’ve converted the frame times to frame rates, so desirable offerings are still at the top left.
The new Radeons look even worse here, no doubt because of their lackluster showing in Skyrim (which I’d probably attribute to a temporary bug). The Nvidia cards are also penalized heavily, which isn’t surprising. Skyrim excepted, the GeForces definitely had a harder time maintaining consistent—and consistently low—frame times than their competitors.
So, there you have it. I hate to end on a down note, but two years after the Radeon HD 5770’s debut, AMD could have done a lot better. The Radeon HD 7770 isn’t a bad product by any means; it just costs way too much. This is a card that belongs at around $130, just below the Radeon HD 6850. It has no business anywhere near $159 or, heaven forbid, $179 like our snazzed-up XFX entrant.
The Radeon HD 7750 is more compelling, despite the awful stock cooling solution. However, it’s still a little too expensive, with a price tag $9 above that of the quicker Radeon HD 5770.
Of course, there is a silver lining. The reality is that the 7770 is almost undoubtedly far cheaper to produce than the 6850; its GPU is half as big, its memory interface is half as wide, and its circuit board likely has fewer layers. The 7770 can also get away with smaller heatsinks without costly heat pipes. It may cost more right now, but prices are almost assured to drop over time—and when they do, the 7770’s ability to nip at the 6850’s heels should turn it into a killer deal for gamers on a budget.
Too bad it’s not there yet.