I'm going to be the lone dissenter here. Years ago I had a Gigabyte P35-DS3L mobo with similar specs to yours, except I think it supported PCIe v1.1 instead of 1.0. No matter what I tried I couldn't get it to work with an PCIe 2.0 XFX Radeon 5750. I returned the thing three times, and finally gave up and bought a GTX 560. Years later I popped the 5750 into a PCIe 3.0 mobo, and it worked flawlessly. Go figure...