About a year ago, I accidentally stumbled upon the performance increase in RF2 when using PCI-e 3.0 vs PCI-e 2.0. Today, during some over-clocking experiments, I discovered the same is true for AC...though not on quite as large of a margin. With significantly higher CPU clocks (in my case 4.5 GHz on an I7-3820 SB-e with PCI-e 2.0 enabled and all AC settings maxed out for testing) Points=11352, fps Ave=77, fps Min=60, fps Max=109, Var=2, CPU usage=45 The CPU was then reset to stock speed (3.6 GHz and PCI-e 3.0 enabled...again all AC settings max) Points=11461, fps Ave=78, fps Min=63, fps Max=127, Var=3, CPU usage=49. The results were compiled after running three test per setup with reboots between each test. Interesting to see that +900MHz...even without throttling yielded less max fps and smoothness with 2.0 vs 3.0 at lower speed.