GeForce + Radeon: Previewing DirectX 12 Multi-Adapter with Ashes of the Singularity
by Ryan Smith on October 26, 2015 10:00 AM ESTAshes GPU Performance: Single & Mixed 2012 GPUs
While Ashes’ mutli-GPU support sees solid performance gains with current-generation high-end GPUs, we wanted to see if those gains would extend to older DirectX 12 GPUs. To that end we’ve put the GeForce GTX 680 and the Radeon HD 7970 through a similar test, running the Ashes’ benchmark at 2560x1440 with Medium image quality and no MSAA.
First off, unlike our high-end GPUs there’s a distinct performance difference between our AMD and NVIDIA cards. The Radeon HD 7970 performs 22% better here, just averaging 30fps to the GTX 680’s 24.5fps. So right off the bat we’re entering an AFR setup with a moderately unbalanced set of cards.
Once we do turn on AFR, two very different things happen. The GTX 680 + HD 7970 setup is an outright performance regression, with performance 40% from the single GTX 680 Ti. On the other hand the HD 7970 + GTX 680 setup sees an unexpectedly good performance gain from AFR, picking up a further 55% to 46.4fps.
As this test is a smaller number of combinations it’s not clear where the bottlenecks are, but it’s none the less very interesting how we get such widely different results depending on which card is in the lead. In the GTX 680 + HD 7970 setup, either the GTX 680 is a bad leader or the HD 7970 is a bad follower, and this leads to this setup spinning its proverbial wheels. Otherwise letting the HD 7970 lead and GTX 680 follow sees a bigger performance gain than we would have expected for a moderately unbalanced setup with a pair of cards that were never known for their efficient PCIe data transfers. So long as you let the HD 7970 lead, at least in this case you could absolutely get away with a mixed GPU pairing of older GPUs.
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andrew_pz - Tuesday, October 27, 2015 - link
Radeon placed in 16x slot, GeFroce installed to 4x slot only. WHY?It's cheat!
silverblue - Tuesday, October 27, 2015 - link
There isn't a 4x slot on that board. To quote the specs..."- 4 x PCI Express 3.0 x16 slots (PCIE1/PCIE2/PCIE4/PCIE5: x16/8/16/0 mode or x16/8/8/8 mode)"
Even if the GeForce was in an 8x slot, I really doubt it would've made a difference.
Ryan Smith - Wednesday, October 28, 2015 - link
Aye. And just to be clear here, both cards are in x16 slots (we're not using tri-8 mode).brucek2 - Tuesday, October 27, 2015 - link
The vast majority of PCs, and 100% of consoles, are single GPU (or less.) Therefore developers absolutely must ensure their game can run satisfactorily on one GPU, and have very little to gain from investing extra work in enabling multi GPU support.To me this suggests that moving the burden of enabling multi-gpu support from hardware sellers (who can benefit from selling more cards) to game publishers (who basically have no real way to benefit at all) is that the only sane decision is not invest any additional development or testing on multi gpu support and that therefore multi GPU support will effectively be dead in the DX12 world.
What am I missing?
willgart - Tuesday, October 27, 2015 - link
well... you no longer need to change your card to a big one, you can just upgrade your pc with a low or middle entry card to get a good boost! and you keep your old one. from a long term point of view we win, not the hardware resellers.imagine today you have a GTX970, in 4 years you can get a GTX 2970 and have a stronger system than a single 2980 card... specialy the FPS / $ is very interesting.
and when you compare the setup HD7970+GTX680, maybe the cost is 100$ today(?) can be compared to a single GTX980 which cost nearly 700$...
brucek2 - Tuesday, October 27, 2015 - link
I understand the benefit to the user. What I'm worried is missing is incentive to the game developer. For them the new arrangement sounds like nothing but extra cost and likely extra technical support hassle to make multi-gpu work. Why would they bother? To use your example of a user with 7970+680, the 680 alone would at least meet the console-equivalent setting, so they'd probably just tell you to use that.)prtskg - Wednesday, October 28, 2015 - link
It would make their game run better and thus improve their brand name.brucek2 - Wednesday, October 28, 2015 - link
Making it run "better" implies it runs "worse" for the 95%+ of PC users (and 100% of console users) who do not have multi-GPU. That's a non-starter. The publisher has to make it a good experience for the overwhelmingly common case of single gpu or they're not going to be in business for very long. Once they've done that, what they are left with is the option to spend more of their own dollars so that a very tiny fraction of users can play the same game at higher graphics settings. Hard to see how that's going to improve their brand name more than virtually anything else they'd choose to spend that money on, and certainly not for the vast majority of users who will never see or know about it.BrokenCrayons - Wednesday, October 28, 2015 - link
You're not missing anything at all. Multi-GPU systems, at least in the case of there being more than one discrete GPU, represent a small number of halo desktop computers. Desktops, gaming desktops in particular, are already a shrinking market and even the large majority of such systems contain only a single graphics card. This means there's minimal incentive for a developer of a game to bother soaking up the additional cost of adding support for multi GPU systems. As developers are already cost-sensitive and working in a highly competitive business landscape, it seems highly unlikely that they'll be willing to invest the human resources in the additional code or soak up the risks associated with bugs and/or poor performance. In essence, DX12 seems poised to end multi GPU gaming UNLESS the dGPU + iGPU market is large enough in modern computers AND the performance benefits realized are worth the cost to the developers to write code for it. There are, after all, a lot more computers (even laptops and a very limited number of tablets) that contain an Intel graphics processor and an NV or more rarely an AMD dGPU. Though even then, I'd hazard a guess to say that the performance improvement is minimal and not worth the trouble. Plus most computers sold contain only whatever Intel happens to throw onto the CPU die so even that scenario is of limited benefit in a world of mostly integrated graphics processors.mayankleoboy1 - Wednesday, October 28, 2015 - link
Any idea what LucidLogix are doing these days?Last i remember, they had released some software solutions which reduced battery drain on Samsung devices (by dynamically decreasing the game rendering quality