I have a AMD Athlon x2 4200+ processor, 2Gb RAM, Antec Earthwatts EA500 500W PSU, and a HIS 4770 video card. I did check the temperature of the card under heavy use, and it's about 65 degrees Celsius, which seems fine to me. increasing the fan speed didn't help at all. Because of this, I didn't think under clocking would do anything if temperature wasn't the problem. However, I underclocked the card from 750Mhz/800Mhz GPU clock/Memory Clock to 700Mhz/700Mhz and the flickering only happened once in an hour. Underclocking it more and I got no more flickering, so I am pretty confused right now to be honest.