You can try going to the CH Hangar for particular issues and a lot of good tips. I have the USB FighterStick, Pro Throttle and pedals and all are working perfectly with USB2 in Win 7 64 bit Home Premium and a system similar to yours (not overclocked though).
One thing I do have that I don't see listed in your post is a purchased and registered version of FSUIPC where I calibrate my controllers. Maybe that's the diff?
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