As far FSX is concerned at any rate.My PC has 2x GTX570 in SLi. When both cards are installed on the MoBo, the PCIe bandwidth automatically adjusts to 8x for each card/slot.With one card in the primary PCIe slot, the bandwidth runs at 16xEven if I disable SLi from the NVIDIA control panel (it gives me no benefit in FSX really) the slots themselves remain at 8x until I remove the second card.Now I don't believe that this should make any difference to FSX performance given that it is CPU bound more than GPU - anyone know differently?

I'll start with the blog that's been thrown around in these forums crusading PCIe 3.0. http://blogs.msdn.co...e-envelope.aspxI haven't personally tested the differences, but apparently there's proof that there is considerable performance loss when using heavy autogen with PCIe 1.0 8x, 16x, and PCIe 2.0 16x. Reported within the blog, it's suggested (or proven, rather) that the PCIe bus is saturated with high autogen settings. 8x compounds this to a great degree.The P67 isn't exactly built for SLI setups. The Z68 would have been a better choice given it's features for SLI/Crossfire users.

The P67 isn't exactly built for SLI setups. The Z68 would have been a better choice given it's features for SLI/Crossfire users.

Why would that be? I have a buddy running SLI on a ASUS P67 Saber with zero issues.

Yes there can be a notable difference. I have written about it here: http://forum.avsim.net/topic/360847-bp0-and-the-pcie-bus-or-why-you-should-have-a-fast-enough-gpu-to-actually-make-use-of-your-cpu/page__p__2238337#entry2238337

Yes there can be a notable difference. I have written about it here: http://forum.avsim.n...37#entry2238337

...I haven't personally tested the differences, but apparently there's p..roof that there is considerable performance loss when using heavy autogen with PCIe 1.0 8x, 16x, and PCIe 2.0 16x. Reported within the blog, it's suggested (or proven, rather) that the PCIe bus is saturated with high autogen settings. 8x compounds this to a great degree...

Wow - interesting reading and certainly not the answer I was expecting, thanks gents!I guess seeing as I am not really playing anything else on the PC other than FSX at the moment (and BF3 is one of the very few games where SLi is a must for a locked in 60FPS) I will whip the second card out and do a bit of "User experience" based testing.I have gone cold turkey on FRAPs at the moment, as with it on I spend all my time staring at and obsessing over a small yellow number rather than actually flying, so at this stage any reports of a positive benefit would be based on circumstantial observation and may well be a placebo, but I will suck it and see and let you know.Cheers

A bit early to tell for sure, but it does look like removing the second card and restoring my PCIe to 16x along with adding a small OC to the GPU has resulted in less noticeable micro-stuttering and an improvement in detailed ground texture loading times...seems textures are loading to maximum LOD faster when I am low and slow (or low and fast-ish!)Again, could be placebo, but I will keep playing and see.