To sli or not to sli that is the question

[styckx]

Maxing out the GPU is easy.

[ttjph]

I've shown that in several situations I can get the GPU to 100%.

But only in 50% of your examples AND with an outdated GPU chip - I don't wish to labour the point but the sim engine, without a doubt, has been shown to be predominantly CPU-limited. 50% of your own examples show this. If you'd have been using the same CPU with a better GPU it would project your results to show that, eventually, all of your examples would have lower FPS with higher settings without your GPU ever hitting 100%.

My video card is a few years old, but so is my CPU - there's at least 50% more performance available from a recent i5. So I could make the same argument in reverse...

deniswick above reports getting a massive increase in fps when he Crossfired his 6870s - which, on the face of it, are reasonably capable cards individually - so he clearly wasn't CPU limited for that particular test.

It does depend on your exact system, and it also depends on the graphics settings you want to run and the route you're running on. If I'm happy to run without SSAA, and I'm on a 'heavy' route such as WCML-N, then I'm definitely CPU limited. If I want 2x2 SSAA on an older, simpler route then I'm GPU limited. (In practice, I've carefully chosen my graphics options to make maximum use of both and to achieve a frame rate I consider acceptable.)


If you're thinking of upgrading, do some tests on different routes while watching your GPU usage using nVidia Inspector or similar (styckx, are you using FRAPS for that overlay?). If it doesn't reach 99-100% with your desired settings, then there's no point adding more graphics horsepower. If it does hit 100%, and turning off shadows and SSAA and reducing resolution gives you more fps, then you have CPU to spare and might benefit from SLI (although depending on your current card, just replacing it may also be an option).