We used to be friends, you know, back in the day. Me and Fatal1ty, I mean. We worked at the same ISP, him taking customer calls on the support front lines and me in the back room, keeping the network running. He came to me when he couldn’t fix a problem. We even played Quake together, before he became the biggest gamer in the world over the successive 18 months or so and I became, well, a cable modem admin.
Sometimes I look back and think, had circumstances been differenthad nature, for instance, given me a vastly superior set of skills, abilities, looks, social graces, age, and intelligencethat I could have had the same sort of success that he has. But then I wonder: could I have handled it? Not the pressure of competition or any of that, but the sheer extremeness of being so extreme. Drinking the energy drinks, wearing the bright colors, the hair gel. And I realize, I probably could not have.
Had I somehow managed it, though, without spontaneously combusting, I expect that this new video card from AMD, the Radeon HD 5970, would surely have become my weapon of choice.
The Radeon HD 5970
AMD offers its competition a sip of Hemlock
In spite of its singular name, the Radeon HD 5970 is in fact a dual-GPU graphics card in the tradition of the Radeon HD 4870 X2. Codenamed “Hemlock” during its developmentor at least during its pre-launch marketing stagethe 5970 sports two of the Cypress GPUs that power the Radeon HD 5870. Each GPU has its own 1GB bank of GDDR5 memory, and the card itself is longer than a fourth-grade piano recital, measuring out to 12.16″ or 309 mm. Here, have a look at how the 5970 measures up against some common varieties of graphics cards.
From left to right: GeForce GTX 295, Radeon HD 5970, Radeon HD 5870, Radeon HD 4890
At 9.5″, the Radeon HD 4890 looks positively puny by comparison. Even the considerable 10.5″ span occupied by the GeForce GTX 295 looks way less extreme. The crazy thing is that the 5970’s Batmobile-inspired plastic shroud extends roughly half and inch past the end of the board itselfand its primary purpose is to look cool.
AMD points out that the 5970’s length is compliant with the ATX spec, but we haven’t seen a video card this long for many, many moons. I fear many PC cases these days aren’t really built to accommodate such a beast, especially the mid-towers. The bottom line here is that you’ll want to measure for clearance in your own case before hitting the “Buy” button at your favorite online retailer. Then again, if you’ve ponied up for an Obsidian, you surely need not worry.
Dual dual-link DVI ports flank a mini-DisplayPort, er, port
Due to the need to free up an entire slot backplate for the cooler’s exhaust, the 5970 has a different port config than the rest of the Radeon HD 5000 series. The HDMI port has been deleted, while the DisplayPort output has been hit with a shrink ray and reduced to Mini size. Despite the changes, AMD says the 5970 can still drive up to three displays simultaneously, and 5970 cards will ship with a pair of adapters: one that converts Mini DisplayPort to regular DisplayPort, and another of the DVI-to-HDMI variety.
A combo of six- and eight-pin connectors provides power
As the combination of six- and eight-pin power plugs portends, the 5970’s max power draw is rated at 294W, just under the 300W limit imposed by the PCIe spec. The good news on the power front comes at idle, where the 5970 inherits the very nice reductions in power draw achieved by the Cypress GPU and its memory controller. To that, this card adds another wrinkle: when it’s not needed, the second GPU enters a low-power sleep state (AMD likens it to the ACPI S1 state, if you must know), which should blow Al Gore’s skirt up. As a result, the 5970’s idle power draw is rated at 42W.
Two GPUs, but just a single external CrossFire connector
The Cypress GPUs on either side of the PLX PCIe bridge chip
The 5970’s dimensions and peak power draw are so ample because the card has to accommodate two copies of what is currently the fastest GPU on the market. This really is “CrossFire on a stick,” as we like to say, and the performance potential from such a beast is naturally quite considerable. Situated between the two GPUs in the picture above, under a metal cap, is a PCI Express switch chip from PLX, the same model used in the Radeon HD 4870 X2. This chip can support a trio of PCIe x16 links: one to each of the GPUs and a third to the PCIe x16 slot in the host system.
Like any two GPUs in a CrossFire pair, the 5970’s Cypress chips communicate with each other by means of those PCIe links and via a dedicated CrossFire interconnect, as well. Gone is the GPU-to-GPU “sideport” connection that was present on the 4870 X2. AMD says improvements to its drivers and to the performance of its CrossFire interconnect have rendered the sideport link unnecessary, even though the CrossFire interconnect’s physical bit rate, at 7.92 Gbps, remains similar.
Although the magic is all taking place on a single card, the 5970 is subject to the same limitations as any multi-GPU solution. That means you won’t always be able to take advantage of both GPUs in a new game until you’ve installed a driver update with a CrossFire profile for it. Also, you can expect to see something less than twice the performance of a single GPU, because multi-GPU performance rarely scales up perfectly.
Still, we must admit that AMD has made great strides in its multi-GPU support since committing to these dual-GPU cards. The latest bit of evidence on that front is the fact that the 5970’s release drivers will support AMD’s Eyefinity multi-monitor gaming capability. This is a first, and the support currently only extends to 22 games. We haven’t yet had time to try it out for ourselves, either. Still, it is a positive sign.
Speaking of signs, the one in the store next to the 5970 will read “$599.99” or thereabouts. That’s not cheap, but it’s somewhere between the price for two Radeon HD 5850s and two Radeon HD 5870s, so it has its own cruel logic. This is not a bargain-bin item by any stretch. The larger question is whether you’ll be able to buy one at any price, given the shortages we’ve seen on Cypress-based 5850 and 5870 cards, coupled with reports of yield issues at TSMC on 40-nm chips. When we quizzed AMD about 5970 availability, they could only say they expect the 5970 to be selling today at multiple online retailers and that supply “should be steady” through the holidays. Whether it’ll be a steady drip or a steady torrent remains to be seen, but I’m betting on the drip at this point.
Bending the envelope
When it came time to choose the 5970’s clock speeds, AMD encountered a no doubt vexing tradeoff. In order to stay within the 300W power envelope dictated by the PCIe specification, they had to dial back clock speeds considerably from Radeon HD 5870 levels. (That’s probably why this beast isn’t called the Radeon HD 5870 X2.) In fact, the clock speeds they chose are right at Radeon HD 5850 levels: 725MHz for the GPU, and 1GHz (or 4GT/s) for the GDDR5 memory. Here’s a look at how the 5970 stacks up, in peak theoretical performance.
|GeForce GTX 285||21.4||53.6||26.8||166.4||744||1116|
|GeForce GTX 295||32.3||92.2||46.1||223.9||1192||1788|
|GeForce GTX 285 SLI||42.9||107.2||53.6||332.8||1488||2232|
|Radeon HD 4870 X2||24.0||60.0||30.0||230.4||2400||–|
|Radeon HD 5850||23.2||52.2||26.1||128.0||2088||–|
|Radeon HD 5870||27.2||68.0||34.0||153.6||2720||–|
|Radeon HD 5970||46.4||116.0||58.0||256.0||4640||–|
These days, I feel like we should attach as many caveats to that table as one might to a federal budget resolution. These are simply theoretical peak values, and they are in some cases quite academic. You’re rarely going to hit the peak pixel fill rate on one of these cards, for instance, since memory bandwidth will likely limit you first. The GeForces probably won’t ever reach their peak dual-issue shader FLOPS numbers, and I doubt the Radeons will achieve more than 80% of their peak compute capacity when executing pixel shaders. On top of all that, we’ve just thrown in the numbers for the multi-GPU solutions, even though they’ll rarely scale linearly.
With that said, you can see above what AMD’s compromise on clock speeds has wrought. The 5970 is still undoubtedly the most capable single-card solution around, but it’s closer to two 5850s than it is to two 5870s. (The GPUs on the 5970 don’t have any functional units disabled, so the 5970 should be slightly faster than a pair of 5850s in terms of shader and texturing capacity.)
The more dramatic comparison, though, is the 5970 versus two GeForce GTX 285 cards in SLI. The 5970 has more than double the peak shader capacity, but it’s pretty similar in terms of texture fill ratesand the GTX 285 SLI config has substantially higher memory bandwidth. Thanks to its 256-bit memory interface, Cypress was already balanced pretty heavily in favor of shader power rather than memory bandwidth. Doubling up on Cypress chips amplifies that fact, especially at these clock speeds, where the 5970 trails some competing solutions. The implications of these numbers should be fairly straightforward: in cases where performance is bound primarily by memory bandwidth or texture filtering, the 5970 may not look as impressive as one might have hoped.
The thing is, one could argue that the 300W PCIe spec for video cards is more of a speed limit than a credit limit. If you go over it, bad things might happen, but the system won’t necessarily stop working immediately. In fact, you might just end up having more fun. Honest, officer. And we know the Cypress GPU and its GDDR5 memory are both good for higher clock speeds, as the Radeon HD 5870 attests.
AMD didn’t want to tread formally beyond 300W, so it has decided to do so informally, instead, by enabling users to overclock the 5970 deep into 400W territory. The firm claims it has taken on considerable expense in the design and production of 5970 cards in order to give them ample headroom. The GPUs, it says, are screened for high speeds and low leakage. The DRAMs are rated for 5Gbps operation, just like on the 5870, even though they only operate at 4Gbps by default on this card. The electronics, including the capacitors and voltage regulators, are built to higher standards. And the cooler’s “massive” vapor chamber can dissipate up to 400W.
So, you know, it’s a Ferrari 599 GTB, and the local speed limit is 55 MPH. Wink, wink.
The 5970 laid bare
These Hynix GDDR5 DRAMs are rated for 5 Gbps operation
To enable its customers’ potential delinquency, AMD has raised the caps on its Overdrive overclocking control panel for the 5970, pushing the limits to 1GHz for the GPU and 1.5GHz (or 6 GT/s) for the memory. The company also expects its board partners to offer voltage tweaking tools with their 5970 products, and it supplied us with a rudimentary example of such a tool.
Those sliders promise granularity, but it’s a mirage. You get two settings here: default and peak. Fortunately, that’s pretty much all you’ll need to make good on what AMD strongly hints is the 5970’s potential: the same clock speeds as the Radeon HD 5870, or 850MHz/1.2GHz GPU and DRAM, respectively.
We didn’t get very far at all in our overclocking attempts without the voltage tweak, but at the higher voltages, we hit 5870 levels with very little drama. In fact, we’ve tested at those speeds and included full results in this article.
Do remember a couple of things, though. First, you’ve got to overclock both GPUs individually in the control panel in order to see any real performance gain. Second, although the clock speed settings in the Overdrive tool will persist after a reboot, the higher voltage settings did not, in our experience. This combination made for some interesting times, let me tell you.
In fact, we had so much fun sorting out that issue that we decided against pushing the 5970’s clocks beyond 5870 levels. We’ll leave that fun up to you.
Regardless of how easy AMD has decided to make it, this is still real overclocking, with no guarantees about likely clock speeds or what bad things may happen when you exceed stock settings. You’ll have to engage in real overclocking to get a 5970 that runs at these speeds, too, because AMD plans to limit the fake “overclocking” conducted by board vendors, the sort where they set higher default speeds and back up the cards with full warranties. AMD even says it has a mechanism in place to cap default clock speeds, and it will prevent board vendors from pushing too far past the 300W limit. That may change eventually; plans are afoot to enable dual 8-pin power connectors on future 5970 cards, but don’t expect to see such an animal until next year.
We’ve tested the 5970 against a handful of other high-end solutions in some of the very latest games. I should note that we wanted to include a few things, such as Dragon Age: Origins and the Heaven DX11 benchmark, that don’t yet have CrossFire profiles. In the interest of exploring the 5970’s true potential, we’ve skipped those applications for now, but we may come back to them in the future.
The card you see above is Asus’ version of the Radeon HD 5870, a true retail product that’s replaced the AMD reference cards on our test bench. Asus ships this card with a Steam coupon for DiRT 2 and a three-year warranty that, blessedly, does not require registration of the product within a certain number of days.
The thing that makes this Asus card interesting is that it comes with a voltage-tweaking tool, much like what AMD expects its partners to offer for the 5970.
Asus’ Smart Doctor tool offers voltage control
I’ve not yet pushed this 5870 to its limits, but I should note that the voltage slider tops out at a somewhat scary 1.5V.
Also, one must look at the screenshot above and ask: Really, AMD? You want to entrust the designer of this interface with the 5970’s crucial overvolting feature? Really?
Our testing methods
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||Core i7-965 Extreme 3.2GHz|
|System bus||QPI 6.4 GT/s (3.2GHz)|
|North bridge||X58 IOH|
|Chipset drivers||INF update 220.127.116.115
Matrix Storage Manager 18.104.22.1683
|Memory size||6GB (3 DIMMs)|
|Memory type||Corsair Dominator TR3X6G1600C8D
DDR3 SDRAMat 1333MHz
|CAS latency (CL)||8|
|RAS to CAS delay (tRCD)||8|
|RAS precharge (tRP)||8|
|Cycle time (tRAS)||24|
with Realtek 22.214.171.12419 drivers
|Graphics|| Radeon HD 4870 X2 2GB PCIe
with Catalyst 8.663.1-091105a-091227E drivers
|Asus Radeon HD 5870 1GB PCIe
with Catalyst 8.663.1-091105a-091227E drivers
| Radeon HD 5970
with Catalyst 8.663.1-091105a-091227E drivers
|Asus GeForce GTX 285 1GB PCIe
with ForceWare 195.39 drivers
|Dual Asus GeForce GTX 285 1GB PCIe
with ForceWare 195.39 drivers
| GeForce GTX 295 2GB PCIe
with ForceWare 195.39 drivers
|Hard drive||WD Caviar SE16 320GB SATA|
|Power supply||PC Power & Cooling Silencer 750 Watt|
|OS||Windows 7 Ultimate x64 Edition RTM|
|OS updates|| DirectX
August 2009 update
Thanks to Corsair for providing us with memory for our testing. Their quality, service, and support are easily superior to no-name DIMMs.
Our test systems were powered by PC Power & Cooling Silencer 750W power supply units. The Silencer 750W was a runaway Editor’s Choice winner in our epic 11-way power supply roundup, so it seemed like a fitting choice for our test rigs.
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 versions of our test applications:
- Borderlands 1.0
- Call of Duty: Modern Warfare 2
- Far Cry 2 1.03
- Left 4 Dead 2 demo
- Resident Evil 5
- FRAPS 3.0.1
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.
Call of Duty: Modern Warfare 2
To test this game, we played through the first 60 seconds of the “Wolverines!” level while recording frame rates with FRAPS. We tried to play pretty much the same way each time, but doing things manually like this will naturally involve some variance, so we conducted five test sessions per GPU config. We then reported the median of the average and minimum frame rate values from all five runs. The frame-by-frame results come from a single, representative test session.
We had all of MW2‘s image quality settings maxed out, with 4X antialiasing enabled, as well.
Any of these graphics cards will run this game quite well, even at this four-megapixel display resolution. In terms of average frame rates and bragging rights, the 5970 is clearly the fastest dual-GPU graphics card, ahead of the GeForce GTX 295. However, only three FPS separates the two cards’ lowest frame rates, and since we’re near the 70 FPS mark, playability obviously isn’t an issue.
Overclocking the 5970 to 850MHz/1.2GHz takes its average FPS just beyond the dual GeForce GTX 285s, but its minimum frame rates are a little lower.
This is my favorite game in a long, long time. I played through Borderlands on a variety of graphics cards, mostly from the Radeon HD 5000 series, and it generally ran quite well. However, I noticed certain areas where frame rates tended to dip on the Radeons, and playing with a GeForce seemed to feel smoother. I figured this would be a good test for the 5970, so I picked one of those spots in the game to use in testing for this review.
This is me finding a sore spot and poking it, of course, so it’s not entirely fair on some levels. Still, games these days tend to run exceptionally well on just about anything, and I wanted to explore a case where the 5970’s additional GPU power had a chance to make a difference.
I tested by playing through the “Krom’s Canyon” level of the game and recording frame rates in 60-second chunks with FRAPS. Since I was playing through the whole level and not just repeating the same thing over and over, I took more samples, recording eight sessions per GPU config. We tested at 2560×1600 resolution with all of the in-game quality options at their max. We couldn’t enable antialiasing, though, since the game’s UT3 engine doesn’t support it.
Obviously, the GTX 295 handles this level of Borderlands better, especially when you’re looking at avoiding low frame rates. That’s a result that comes from a lot of playing in varied parts of the level, though. If we look at the very first one of our testing sessions, which occurs in an area that gives the Radeons particular trouble, the problem is easy to see:
Even the 5970’s frame rates drop to about 30 FPS in certain areas. I’m not sure what’s happening here, but my best guess is that it may have something to do with the way the game and the graphics driver determine which objects are visible. Krom’s Canyon is a long and narrow level. Frame rates seem to drop when you look straight down the canyon, even if your view is largely obstructed by the terrain. Yes, frame rates are still borderline acceptable, but you can definitely feel it when the game slows down.
Whatever’s happening here, the 5970’s prodigious graphics power isn’t sufficient to overcome it. Meanwhile, Nvidia seems to have avoided this problem.
Far Cry 2
We tested Far Cry 2 using the game’s built-in benchmarking tool, which allowed us to test the different cards at multiple resolutions in a precisely repeatable manner. We used the benchmark tool’s “Very high” quality presets with the DirectX 10 renderer and 4X multisampled antialiasing.
The 5970 handles this older, more familiar game more gracefully, easily outpacing the GTX 295, even without the help of overclocking. The default clock speeds are slower than two GTX 285s in SLI, though, at 2560×1600.
Resident Evil 5
I’m shocked to say that this may in fact be the best-looking PC game to date, and it has a very nice built-in benchmarking tool. We used the “variable” benchmark that takes in-game AI and the like into account, and we ran the test five times on each config to account for that variability. Naturally, we had all of the in-game quality options cranked.
The cards here finish in the same order they did in Far Cry 2 and Modern Warfare at 2560×1600. Even the relative performance levels are similar.
Left 4 Dead 2
We tested the demo for Left 4 Dead 2 by recording and playing back a custom timedemo comprised of several minutes of gameplay.
This one upsets the apple cart a bit, as the Radeons take a pronounced and consistent lead over the GeForces. The overclocked 5970 is nearly twice as fast as two GeForce GTX 285s in SLI. Looks like Nvidia has some SLI performance scaling issues here. Two GTX 285s are definitely faster than one, but not by as much as one would expect. Obviously, AMD’s multi-GPU solutions scale much better.
We measured total system power consumption at the wall socket using an Extech power analyzer model 380803. 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 Left 4 Dead at a 2560×1600 resolution. We have a broader set of results here because we’ve included those from our Radeon HD 5700 series review. Although we used older drivers for most of the cards in that review, we don’t expect that to affect power consumption, noise, or GPU temperatures substantially.
The 5970 does indeed achieve relatively modest power consumption at idle, much less than the GeForce GTX 295 or the 4870 X2. Not bad.
At its default speed and voltage, the 5970’s power draw under load is surprisingly modestlower than the GTX 295’s and considerably less than the 4870 X2’s. One wonders whether AMD could have pushed a little harder on clock speeds, looking at these numbers. Then again, the overvolted and overclocked 5970 draws an awful lot of power.
We measured noise levels on our test system, sitting on an open test bench, using an Extech model 407738 digital sound level meter. The meter was mounted on a tripod approximately 8″ from the test system at a height even with the top of the video card. We used the OSHA-standard weighting and speed for these measurements.
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.
The big boost in power consumption that comes from overclocking the 5970 translates pretty directly into higher noise levels. The 5970’s fan controller responds to the additional load by cranking up the blower speed, and the difference is noticeable.
Just for kicks, I tried manually setting the 5970’s blower at max speed and taking a reading. The result: a painful 70.5 dB. Thank goodness it rarely needs to go there.
Fortunately, the 5970 is nice and quiet at idle, unlike the rather annoying hiss of the GeForce GTX 295.
For most of the cards, we used GPU-Z to log temperatures during our load testing. In the case of multi-GPU setups, we recorded temperatures on the primary card. However, GPU-Z didn’t yet know what to do with the 5700- and 5800- series cards, so we had to resort to running a 3D program in a window while reading the temperature from the Overdrive section of AMD’s Catalyst control panel.
At its stock speeds, the 5970 sticks with AMD’s recent tradition of keeping GPU temperatures fairly low, as these things go. When overclocked, though, the 5970 gets very hot. The overclocked config was fairly stable for us in testing, but it’s definitely gonna run warmer.
What to make of the Radeon HD 5970? On the one hand, it’s clearly the fastest graphics card you can plug into your PC, easily outpacing the previous champ, the GeForce GTX 295. This one seemed like an obvious winner, given that it has two of AMD’s excellent Cypress GPUs onboard. That means all sorts of goodness we haven’t really discussed yet in the context of this review, including a DirectX 11-capable feature set (which no Nvidia GPU has yet delivered) and the highest texture filtering quality on the market. At its default speeds, the card’s power draw, thermals, and acoustics are all quite good, too. There’s lots to like here.
AMD’s new product stack
On the other hand, the 5970 is, well, extreme in various ways. The 12″-plus board length is the most obvious candidate, followed closely by the need to overvolt and overclock the productand void your warrantyin order to achieve its true potential. Once you’ve done so, the 5970 will draw more power than it probably should through its aux power connectors, and it will be one hot and loud card, too.
Then there’s the inescapable fact that even today’s best-looking games don’t require anything more than a single Cypress GPU to achieve smooth-as-glass playback at a four-megapixel display resolution. To take full advantage of the 5970’s sheer power, you’ll need to do something extreme, like using an Eyefinity multi-monitor setup or turning on AMD’s supersampled antialiasing. Or you’ll have to justify the purchase in the name of future-proofing, aiming for the fabled Games That Don’t Exist Yet as your main target. I’m in no way against having this measure of graphics power on tap, but the age of console ports has endured another Christmas season, as our new-title-fortified benchmark suite has demonstrated. PC graphics have just outstripped the requirements of today’s games, and game developers have responded by releasing sequels with similar graphical requirements several years in a row now. I’m hopeful for the upcoming DX11 games, but skeptical they will make good use of dual Cypress chips.
Then there’s the $599 price tag and the murky availability picture.
Add it all up, and the 5970 isn’t a bad product by any stretch, but it is very much a niche product in a way its predecessor, the Radeon HD 4870 X2, was not. One wonders how many people will buy these things.
Then again, I’ve never been any good at figuring out the calculus of extremeness, as I’ve said. There’s no doubt the 5970 is the most extreme graphics card you can buy, and for some folks, I suppose, that will be all that matters.