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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Ryan Smith - Thursday, December 22, 2011 - link
Since 1920x1200 has already been commented on elsewhere I'm just going to jump right to your comment on minimum FPS.I completely agree, and we're trying to add it where it makes sense. A lot of benchmarks are wildly inconsistent about their minimum FPS, largely thanks to the fact that minimum FPS is an instantaneous data point. When your values vary by 20%+ per run (as minimums often do), even averaging repeated trials isn't nearly accurate enough to present meaningful results.
CeriseCogburn - Thursday, March 8, 2012 - link
HardOCP shows long in game fps per second charts that show dips and bottom outs are more than one momentary lapse and often are extended time periods of lowest frame rate runs, so I have to respectfully disagree.Perhaps the fault is fraps can show you a single instance of lowest frame rate number, and hence it's the analysis that utterly fails - given the time constraints that were made obvious, it is also clear that the extra work it would take for an easily reasoned and reasonable result that is actually of worthy accuracy is not in the cards here.
thunderising - Thursday, December 22, 2011 - link
Okay. This card has left me thrilled, but wanting for more. Why?Well, for example, every reviewer has hit the CCC Core and Memory Max Limits, which turns into a healthy 10-12% performance boost, all for 10W.
What, legit reviews got it to 1165MHz core and 6550Mhz memory for a 21-24% increase in performance. Now that's HUGE!
I think AMD could have gone for something like this with the final clocks, to squeeze out every last bit of performance from this amazing card:
Core - 1050 MHz
Memory - 1500 MHz (6000MHz QDR)
This was not only easily achievable, but would have placed this card at a 8-10% increase in performance all for a mere <10W rise in Load Power.
Hoping for AIBs like Sapphire to show their magic! HD7970 Toxic, MmmmmmM...
Otherwise, fantastic card I say.
Death666Angel - Friday, December 23, 2011 - link
Maybe they'll do a 4870/4890 thing again? Launch the HD7970 and HD7970X2 and then launch a HD7990 with higher clocks later to counter nVidia.... Who knows. :-)Mishera - Sunday, December 25, 2011 - link
They've been doing it for quite some time now. Their plan has been to release a chip balancing die size, performance, and cost. Then later to compete on high end release a dual-chip card. Anand wrote on this a while ago with the rv770 story (http://www.anandtech.com/show/2679).Even looking at the picture of chip sizes, the 7970 is still a reasonable size. And this really was a brilliant move as though Nvidia has half the marketshare and does make a lot of money from their cards, their design philosophy has been hurting them a lot from a business standpoint.
On a side note, Amd really made a great choice by choosing to wait until now to push for general computing. Though that probably means more people to support development and drivers, which means more hiring which is the opposite way Amd has been going. It will be interesting to see how this dichotomy will develop in the future. But right now kudos to Amd.
CeriseCogburn - Thursday, March 8, 2012 - link
Does that mean amd is abandoning gamers as we heard the scream whilst Nvidia was doing thus ?I don't quite get it - now what nvidia did that hurt them, is praise worthy since amd did it, finally.
Forgive me as I scoff at the immense dichotomy...
"Perfect ripeness at the perfect time" - sorry not buying it....
privatosan - Thursday, December 22, 2011 - link
PRT is a nice feature, but there is an failure in the article:'For AMD’s technology each tile will be 64KB, which for an uncompressed 32bit texture would be enough room for a 4K x 4K chunk.'
The tile would be 128 x 128 texels; 4K x 4K would be quite big for a tile.
futrtrubl - Thursday, December 22, 2011 - link
I was going to comment on that too. A 4k x 4k x 32bit (4byte) texture chunk would be around 67MB uncompressed. For a 32bit texture you could only fit a 128x128 array in a 64KB chunk. An 8bit/pixel texture could be 4k*4kStonedofmoo - Thursday, December 22, 2011 - link
Thanks for the review. A request though...To the hardware sites doing these reviews, many of us in this day and age run dual monitor or more. It always frustrates in me in these reviews that we get a long write up on the power saving techniques the new cards use, and never any mention of it helps those of us running more than one display.
For those not in the know, if you run more than one display on all the current generations the cards do NOT downclock the GPU and memory nearly as much as they do on single montor configurations. This burns quite a lot more power and obviously kicks out more heat. No site ever mentions this which is odd considering so many of us have more than one display these days.
I would happily buy the card that finally overcomes this and actually finds a way of knocking back the clocks with multi-monitor setups. Is the new Radeon 7xxx series that card?
Galcobar - Thursday, December 22, 2011 - link
It's in the article, on the page entitled "Meet the Radeon 7970."Ryan also replied to a similar comment by quoting the paragraph addressing multi-monitor setups and power consumption at the top of page of the comments.
That's two mentions, and the answer to your question.