I can't believe this comes up so often, yet most people forget what was said in similar threads just days ago.
No offence of course, i know that we don't always have the time to read every single post, it just seems strange to me that an important issue such as system component optimization is the one to get overlooked while we spend pages upon pages arguing over the smallest details
Anyway, the short version is this.
A lot of games run different on similar cards from different manufacturers. This is not always due to purposeful optimization, it's just that sometimes the way the code works is slightly better suited for one architecture or the other. Both Ati and nVidia are affected from this, because they use different architectures.
However, we can still make some informed guesses with the information we have at hand.
1) SoW will use DX9,10 and 11 modes. So there's no OpenGL which gave nVidia the advantage in IL2.
2) If you buy the latest cards (nVidia 5xx or Ati 6xxx series), they are all good in terms of power consumption and heat generation. If however you want to choose between the previous generation (nVidia 4xx or Ati 5xxx) and you care about these things, be informed that the single GPU nVidia 480 on its release was marginally faster, no more than 5%, than the dual GPU Ati 5970, but on the lower end of the resolution spectrum only. Ati took the lead as resolutions went higher, important to note for people with multiple monitors.
At the same time the 480 ranked similar if not higher to the 5970 in terms of power consumption and heat generation and the advantage of being the fastest single GPU solution didn't mean much because it was priced almost as high as Ati's dual GPU offerings.
This meant that for 90$ more you could get the dual GPU Ati 5970 which was a better deal overall (less risk of heat induced wear and tear and lower power needs for an overall similar performance). That's why they couldn't compete with Ati initially and the reason that prompted all the improvements and rebranding as the 5xx series, which is now much better than the original 4xx series of cards.
3) Due to the differences in architecture, it tends to go like this:
Go with nVidia 4xx,5xx or Ati 68xx if you are going to make significant use of tesselation.
Go with Ati 59xx if you are not going to use tesselation much, as it's faster in the other tasks.
Go with Ati 69xx if you want both.
The Ati 6xxx series is actually two product lines based on different chips, so it needs some clarification. The 68xx is focused on tesselation but is a bit slower in other tasks, so it's similar to the nVidia way of doing things. The 69xx however is rumored to have the tesselation performance of nVidia's 5xx series coupled with the non-tesselation performance of Ati's 5xxx series. I guess this will be the best of both worlds and the most expensive series for a while.
4) Know your gaming needs! I can't stress this enough, it saves loads of money that could go towards buying other important stuff, like for example extra RAM and a solid state drive to load up those maps faster. In our case, tesselation is still mostly used in a handful of first person shooters. On the other hand, according to Oleg Maddox, SoW is not going to make use of tesselation initially because they would have to rework a lot of the models to make them compatible.
If we sum everything up in our effort to make an informed guess (it's still a guess), it's clear that for SoW the winner seems to be the single GPU Ati 5870 or the dual GPU Ati 5970.
The reason is simple. Why pay money for better tesselation performance when the game won't make use of it? Especially since that performance tends to come at a price premium, or even at the expense of perfomance in the other fields of graphics processing which will probably have more of an effect on running SoW properly.
Hope it helps
