Im trying to max out my 7900GT. Ive got my memory up to 1900mhz, but I'm a little bit confused on the core. If i set it to 640mhz in coolbits and click on "Test Changes" it will pass all day long. but when I try to run the artifact check in ATI Tool I start getting artifacts at about 615mhz. The odd thing is I have been playing around with it today at 640 and I dont see any noticeable artiffacts in HL2: ep1, COD2, or 3dmarks. Is ATI Tool just overly sensitive or is coolbits not working the card hard enough when testing the settings?