@5t3v0 - it might be Vista. If you looked at the link I posted page 9 re: C1E and EIST, it seems to discuss XP etc. But I will tell you this: I was NOT getting a voltage drop (just the multiplier reduction, according to CPU-Z) until I followed the directions in that link. Namely, Control Panel --->Performance & Maintenance ----->Power Options -----> Enable "Minimal Power Management."
@mrfatboy - thanks for checking with Giga Support re: the F4 Bios. It does, indeed, add a line to the boot screen re: CPUID. I don't have enough knowledge to judge whether this is something that's necessary for optimal performance. So I've reverted to F2, since I'm not experiencing any problems with O/C, Ram timings, temps, or voltages.
Regards,