Got two of the FX-797G-TDFC and they are defective when the cards are ran at 100% GPU usage. Stock settings GPU @ 1050mhz, Memory @ 1500mhz, and Power control setting @ 0%. It does not matter whether the cards are in CrossFireX enabled mode or Disabled mode. Have also tried this with (both cards) just a single card in the system at a time. Here is what happens. The card (s) runs great until in hits 100%. At the moment of 100% the GPU core clock starts osculating from 537mhz to 1000mhz. Here is a list of programs I have used and it happens every time it hits 100% GPU usage: 1. Heaven 3.0 2. 3DMark 11 3. 3D Vantage 4. Windows Experience 5. Crysis 1 6. Crysis 2 7. Battle Field 3 8. PC Mark 7 9. FurMark 1.10.4 FurMark (Benchmark preset: 1080) is the quickest program to run to produce the same results. I first noticed this when running GPUShark v0.6.7 to monitor the card (s). Also used GPUZ v0.6.7 and logged to file to verify the results. Then loaded MSI AfterBurner to monitor and log the results and this is where the numbers from 537mhz to 1000mhz showed up. The core clock is very erratic once the GPU hit 100% and the VDDC was a constant 1.213v. At first I thought it might be a driver issue. Started with Catalyst 13.1, then moved down to Cat 12.10, then down to 12.8 Everytime I uninstalled a driver, I ran the AMD Cleanup util 22.214.171.124 and Driver Sweeper and then ran CCleaner to remove any leftover registry entries. System information: Windows 7 64bit Ultimate with latest patches and updates Mother Board: Asus Rampage IV Extreme Bios v3301 Processor: Intel I7 3930K Ram: 32 gig DDR3 2134 Gskill Power Supply: SilverStone Olympus 1500 VGA Card 1: in slot 1 or BusID 1 FX-79G-TDFC VGA Card 2: in Slot 3 or BusID 3 FX-79G-TDFC Temps are fine. Max during Furmark 63c Max while running other programs 70c Has anyone else ran into this situation? Once a GPU hits 100% usage does it clock itself down?