AMD Radeon HD 7970 Review: 28nm And Graphics Core Next, Together As One
by Ryan Smith on December 22, 2011 12:00 AM EST- Posted in
- GPUs
- AMD
- Radeon
- ATI
- Radeon HD 7000
Civilization V
Our final game, Civilization 5, gives us an interesting look at things that other RTSes cannot match, with a much weaker focus on shading in the game world, and a much greater focus on creating the geometry needed to bring such a world to life. In doing so it uses a slew of DirectX 11 technologies, including tessellation for said geometry, driver command lists for reducing CPU overhead, and compute shaders for on-the-fly texture decompression.
Because of the fact that Civilization V uses driver command lists, we were originally not going to include it in this benchmark suite as a gaming benchmark. If it were solely a DCL test it would do a good job highlighting the fact that AMD doesn’t currently support the feature, but a poor job of actually explaining any hardware/architectural differences. It was only after we saw AMD’s reviewer’s guide that we decided to go ahead and include it, because quite frankly we didn’t believe the numbers AMD had published.
With the GTX 580 and the 6970, the 6970 routinely lost to the GTX 580 by large margins. We had long assumed this was solely due to NVIDIA’s inclusion of DCLs, as we’ve seen a moderate single-GPU performance deficit and equally moderate multi-GPU lead for AMD melt away when NVIDIA added DCL support. The 7970 required that we rethink this.
If Civilization V was solely a DCL test, then our 2560 results would be impossible – the 7970 is winning by 12% in a game NVIDIA previous won by a massive margin. NVIDIA only regains their lead at 1680, which at this resolution we’re not nearly as likely to be GPU-bound.
So what changed? AMD has yet to spill the beans, but short of a secret DCL implementation for just CivV we have to look elsewhere. Next to DCL CivV’s other killer feature is its use of compute shaders, and GCN is a compute architecture. To that extent we believe at this point that while AMD is still facing some kind of DCL bottleneck, they have completely opened the floodgates on whatever compute shader bottleneck was standing in their way before. This is particularly evident when comparing the 7970 to the 6970, where the 7970 enjoys a consistent 62% performance advantage. It’s simply an incredible turnabout to see the 7970 do so well when the 6970 did so poorly.
Of course if this performance boost really was all about compute shaders, it raises a particularly exciting question: just how much higher could AMD go if they had DCLs? Hopefully one day that’s an answer we get to find out.
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chiddy - Thursday, December 22, 2011 - link
Ryan,Thanks for the great review. My only gripe - and I've been noticing this for a while - is the complete non-mention of drivers or driver releases for Linux/Unix and/or their problems.
For example, Catalyst drivers exhibit graphical corruption when using the latest version (Version 3) of Gnome Desktop Environment since its release before April. This is a major bug which required most users of AMD/ATI GPUs to either switch desktop environments, switch to Nvidia or Intel GPUs, or use the open source drivers which lack many features. A partial fix appeared in Catalyst 11.9 making Gnome3 usable but there are still elements of screen corruption on occassion. (Details in the "non-official" AMD run bugzilla http://ati.cchtml.com/show_bug.cgi?id=99 ).
AMD have numerous other issues with Linux Catalyst drivers including buggy openGL implementation, etc.
Essentially, as a hardware review, a quick once over with non-Microsoft OSs would help alot, especially for products which are marketed as supporting such platforms.
Regards,
kyuu - Thursday, December 22, 2011 - link
Why in the heck would they mention Linux drivers and their issues in an article covering the (paper) release and preliminary benchmarking of AMD's new graphics cards? It has nada to do with the subject at hand.Besides, hardly anyone cares, and those that do care already know.
chiddy - Thursday, December 22, 2011 - link
And I guess that AMD GPUs are sold as "Windows Only"?Thanks for your informative insight.
MrSpadge - Thursday, December 22, 2011 - link
There are no games for *nix and everything always depends on your distribution. The problems are so diverse and numerous.. it would take an entire article to briefly touch this field.Exagerating, but I really wouldn't be interested in endless *nix troubleshooting. Hell, I can't even get nVidia 2D acceleration in CentOS..
chiddy - Thursday, December 22, 2011 - link
You have a valid point on that front and I agree, nor would I expect such an article any time soon.However, on the other hand, one would at the very least expect a GPU using manufacturer released drivers to load a usable desktop. This is an issue that was distro agnostic and instantly noticeable, and only affected AMD hardware, as do most *nix GPU driver issues!
If all that was done during a new GPU review was fire it up in any *nix distribution of choice for just a few minutes (even Ubuntu as I think its the most popular at the moment) to ensure that the basics work it would still be a great help.
I will have to accept though that there is precious little interest!
Ryan Smith - Thursday, December 22, 2011 - link
Hi Chiddy;It's a fair request, so I'll give you a fair answer.
The fact of the matter is that Linux drivers are not a top priority for either NVIDIA or AMD. Neither party makes Linux drivers available for our launch reviews, so I wouldn't be able to test new cards at launch. Not to speak for either company, but how many users are shelling out $550 to run Linux? Cards like the 7970 have a very specifically defined role: Windows gaming video card, and their actions reflect this.
At best we'd be able to look at these issues at some point after the launch when AMD or NVIDIA have added support for the new product to their respective Linux drivers. But that far after the product's launch and for such a small category of users (there just aren't many desktop Linux users these days), I'm not sure it would be worth the effort on our part.
chiddy - Friday, December 23, 2011 - link
Hi Ryan,Thanks very much for taking the time to respond. I fully appreciate your position, particularly as the posts above very much corroborate the lack of interest!
Thanks again for the response, I very much appreciate the hard work yourself and the rest of the AT team are doing, and its quality speaks for itself in the steady increase in readers over the years.
If you do however ever find the time to do a brief piece on *nix GPU support after launch of the next generation nVidia and AMD GPUs that would be wonderful - and even though one would definately not buy a top level GPU for *nix, it would very much help those of us who are dual booting (in my case Windows for gaming / Scientific Linux for work), and somewhat remove the guessing game during purchase time. If not though I fully understand :-).
Regards,
Ali
CeriseCogburn - Thursday, March 8, 2012 - link
Nvidia consistenly wins over and over again in this area, so it's "of no interest", like PhysX...AmdInside - Thursday, December 22, 2011 - link
I won't be getting much sleep tonight since that article took a long time to read (can't imagine how long it must have taken to write up). Great article as usual. While it has some very nice features, all in all, it doesn't make me regret my purchase of a Geforce GTX 580 a couple of months ago. Especially since I mainly picked it up for Battlefield 3.ET - Thursday, December 22, 2011 - link
The Cayman GPU's got quite a performance boost from drivers over time, gaining on NVIDIA's GPU since their launce. The difference in architecture between the 79x0 and 69x0 is higher than the 69x0 and 58x0, so I'm sure there's quite a bit of room for performance improvement in games.Have to say though that I really hope AMD stops increasing the card size each generation.