The freezes seem to happen in bursts—e.g. it hasn't happened in a week or so, then I just froze twice in the last 10 minutes. I gamed for many hours without incident last night.
This is what I've checked or done so far without success:
- Taken apart the system and cleaned out dust. I've reseated the RAM and PCI cards, replaced thermal compound on both the CPU and video card.
- Uninstalled/driver-cleaned/reinstalled fresh drivers for video card, sound hardware, chipset, USB.
- Reformatted; reinstalled fresh Windows 7. I also set my BIOS to default when I did this.
- Checked heat at load and idle for relevant components—its always fine.
- Triple-checked overclocks for stability. They always pass, and I've crashed at stock settings anyway.
- Stress tests generate the expected heat and load, without exposing any problems.
- Windows is not generating any minidump files or problem reports for me to check.