In case some of you have not been following the "Live Performance Benchmark..." thread, we had been observing some graphics card performance inconsistencies between different rf2 users. Some users graphics cards (such as my GTX 970) were under-performing in rf2 compared to others with the exact same graphics card at the exact same clock speeds, yet in all other (common) games and benchmarks they were performing normally and as expected again. TechAde managed to figure out what was causing this problem. Graphics cards that were under performing in rf2 than they should have been, were also found to be running their graphics card in PCI-e 2.0 x16 (or lower) mode on the motherboard. And when they switched it up to PCI-e 3.0 x16 mode, the under-performance issue was no more and the cards were now performing correctly and to their fullest again. This is taken from the start of the OP in the "Live Performance Benchmarking..." thread found here (worth a look as well): http://isiforums.net/f/showthread.php/21983-Live-Performance-Benchmarking-Comparison-for-rFactor-2 The higher end your graphics card, the worse the performance loss will be of course. What i can tell as a reference is my GTX 970 was bottlenecked by PCI-e 2.0 x16 which reduced performance by 12% using the "live performance benchmarking.." thread gfx settings. If your card performs better than a GTX 970, you will most certainly not want to be running in anything less than PCI-e 3.0 x16 mode. Some cards even less than my GTX 970 will also benefit but atm we're not sure exactly where the cut off point of benefit from using PCI-e 3.0 x16 over PCI-e 3.0 x8 or PCI-e 2.0 x16 is. I hope to have the answer for you shortly on this. rFactor 2 is the first game/sim that i've used where i've observed a real benefit from PCI-e 3.0. I suppose it was about time.