Multi-GPU Performance in DirectX10

When Vista arrived, Microsoft heavily promoted the benefits the new OS would bring gamers. Gaming was to be an important facet of the new operating system's design -- not added on as an afterthought. A shortcut to a 'Games' folder was added, by default, to Vista's start menu -- right beside music, pictures and documents. The  'Games for Windows' campaign and website was launched to promote Vista as a powerful gaming platform. DX10 was made exclusively for Vista -- forcing all gamers wanting to experience the new API to upgrade to new video cards, and embrace the new OS.

Unfortunately, 'Games for Windows' did not include support for CrossFire or SLI.

It's true.

When Vista was released back in January, most people expected multi-GPU support to be quickly forthcoming. In February, some reviewers thought it  "should be coming in a  couple of weeks"  (link). More recently, some others believed that the drivers should be done "by the end of April" (link). Countless performance reviews of games ran multi-GPU setups and wondered why running more than 1 GPU didn't affect performance much. Many heads were scratched.

But now, in the late summer of 2007, finally, better support for CrossFire and SLI in Vista has arrived.

Vista patch KB936710, re-released in that last week of August, flew pretty low underneath the radar -- most people weren't even aware of its arrival. But this patch, along with KB940105, are vital for any DX10 gamers hoping to get a performance boost with a second video card.

This article will look at how far Vista's support for CrossFire and SLI extends. We used five of the latest DX10 game benchmarks to measure the performance advantage a second 8800 GTS, 8800 GTX, or extra HD 2900 XT can deliver to hardcore PC gamers.

www.neoseeker.com/Articles

So, what do all these benchmarks show us?

For starters, it seems that the belated age of multi-GPU performance in Vista has begun -- but it's still in its infancy.

As of the time of writing of this article (mid-September, 2007), all indication seem to point towards SLI having better driver support than CrossFire. After looking through all the benchmarks, it would be hard to claim otherwise. The only game that benefited from CrossFire support was Lost Planet -- and even then, there was image corruption. Enabling CrossFire actually resulted in a loss of game performance, more often than not, including in the possible PC game-of-the-year, Bioshock. Judging from these numbers, there are probably more than a handful of gamers out there who own two HD 2900 XT's, and are not very impressed by the situation.

But -- if you do own 2 HD 2900 XT's, don't rush out and sell them just yet. The CrossFire-enabling Vista patches are still quite new -- it is very likely that somewhere in Markham, Ontario,  ATI/AMD's driver team is hard at work, trying to smooth out the CrossFire problems.

As for SLI in Vista: things look good. SLI seems ready to meet the big upcoming DX10 titles (i.e Crysis). It is even conceivable that someone shopping for a new gaming rig right now could consider buying a pair of 8800 GTS's over a single 8800 GTX. The BFG 8800 GTS's running in SLI out-performed our Asus EN8800 GTX in Lost Planet, Call of Juarez, and Bioshock. Prices always fluctuate, but according to most online retailers right now, a pair of 8800 GTS cards would cost only between $50 and $100 more than a single 8800 GTX.

Vista and DX10 have been out for about 8 months now -- so it's good to finally see that SLI, and to a far lesser extent CrossFire, have made to the party.