I recently attempted to unlock and overclock my Phenom II 550 BE w/Gigabyte GA-MA770T-UD3P mobo. I did not have any success and eventually used "Load Optimized Settings" in the BIOS and returned my computer to stable running condition. A couple of days later, it would no longer boot. The last info on the black boot screen is "Verifying DMI Pool Data . . . AMD Data Change. . . Update New Data to DMI! Boot From CD/DVD. DISK BOOT FAILURE" (I'm a bit concerned about the exclamation (!) point after DMI). After resetting the CMOS, I get the following message, "CMOS checksum error - defaults loaded. EC Firmware is unstable and BIOS already turn it off." I believe the "checksum error" is expected after a CMOS reset, but what's with the "EC Firmware is unstable?" Does this mean my BIOS is scrogged? Or could it be the CPU? BUT as I said, my computer ran fine for a couple of days after my OC attempt, so I'm skeptical that is the problem. The thing is, my single SATA drive is no longer showing up on the POST splash screen not is it showing up in the BIOS. Only my single optical drive shows up. Could it be coincidental that my HDD is bad and I need to replace that? The HD activity light on the case does blink a bit, but I don't think I hear the spinning like I used to. I don't have another SATA drive to throw in, nor do I have another SATA capable computer to check the drive. Any ideas as to how to diagnose this problem or as to what may be wrong. I need to get this machine back up quick but don't want to buy expensive unneeded parts to do it. Any comments/suggestions will be greatly appreciated. One more thing, I did attempt to boot from my full-install XP Pro disk. It says "entering setup" but eventually gets to a blue screen with the "Windows has shut down" message. Does this indicate that my hard drive IS working?