I have no idea why it constantly flip the frequency between 2D and 3D (500-800). I've tried with CCC Autotune on and off, makes no difference (except that it flips between 500-840). The card is a PowerColor HD4870 PCS+ 1GB. I have no idea if it's Rivatuner or if it's something else. I need another tool that can show realtime GPU frequency and ATT doesn't work in Vista x64. Any ideas anyone? EDIT: It's the Hardware Monitor that causes the frequency to flip. I just checked with GPU-Z running next to it (running with and without Riva's Hardware Monitor, making sure GPU-Z would keep measuring while in the background). Letting GPU-Z monitor by itself showed no weird behavior. ps. while I'm at it, I can't change the values on the auto-fan page even though I've enabled it by setting the value for AutoFanSpeedControl to 3. Tried with CCC Overdrive enabled and disabled, and with manual and auto fanspeed in CCC. Perhaps I need to disable CCC completely?