Q6600 won't run at 3.0 ghz anymore. damage?

[Changnoi]

Last week my system (with Windows Vista 64) began to get very unstable - programs would crash, my anti-virus software became corrupted and my firewall turned itself off and wouldn't allow it to be turned on again.

Because of the latter two things, I thought it was a virus. I tried to find and clean it but couldn't find anything, and problems got worse. So I reformatted my HD and reinstalled Vista.

And had the same problems again. I thought maybe the virus had hid itself on my 1 TB second drive and I was going to have to format that too and lose all my data.

So with a heavy heart I booted from the Vista install disk - which crashed!

How could the virus infect my vista install disk. I realized the problem must be hardware related.

On an off chance I took my Q6600, which had been running at 333 FSB and it's 1.25 VID, back down Auto and 1066 FSB.

Windows install booted, and I re-installed and set everything up again.

I'd hoped it would be perfectly stable like it was before, but it isn't. Firefox crashes every 15 minutes, games crash all the time, processes get dropped. It's better than it is at 1333 FSB though. And it barely POSTS at 3.0 ghz - even with 1.325 Vcore!

My cooling is good, I have an AC Freezer 7 Pro. It was stress tested with Prime 95 and never broke 60c Tcore. It idled at 39c.

Is my CPU damaged? Or is it a virus after all? Mabye both? Shouldn't it run fine at 3.0 ghz? I live in Thailand and the electricity is sketchy - could it have been damaged by a power surge? It seems unlikely since I use a Line-interactive UPS.

What do you guys think?

Here are the rest of the system specs:

Q6600 with AC Freezer 7 Pro
ASUS P5E
2 GB (800) Corsair Valueselect, 2 GB (800) Kingston, 2x512 MB (667) Micron Technology
HD 4870
500 GB Hitachi HD
1 TB WD Caviar Black
2 DVD R/W
Tagan BZ-700w
HP w2408h LCD

 

[CompuTronix]

Sounds like a bad memory module. Remove all but one module, then boot into the DOS environment with a USB flash drive or floppy, and run Memtest - http://www.memtest86.com/download.html - on each individual module.

 

[Changnoi]

I really hope it's just the RAM. I've only had that chip overclocked for 6 months, running about half of the time.

 

[irkjab]

I doubt that the Q6600 would have been damaged by a 3.0ghz overclock, especially with the low volts.

 

[CompuTronix]

I agree. The Q6600 is quite robust, and since Vcore Max is 1.5v, and Tcase Max is 71c, it's unlikely that this stability problem would be caused by the processor.

 

[Changnoi]

I've done as CompuTronix suggested, and every DIMM is showing errors on exactly the same test - #7 the "random number sequence." The Corsair module came up with nearly 1200 errors just by itself.

I'm going to test the DIMMs in my second computer, but I've got the feeling they're going to come up fine because what are the chances they would all go bad at the same time in the same way? If they are bad I'll replace them all with some low latency DDR2 1333 Mushkin.

If they are fine, then I must have a bad memory controller, right? Which means replacing the motherboard...

 

[CompuTronix]

Did you test each module in the same slot? Did you try testing all modules in a different slot? Is the DIMM supply voltage too low?

 

[Changnoi]

The DIMMs were all tested in different slots. I haven't checked the voltage or tweaked it - could a bit more Vdimm help?

 

[CompuTronix]

It wouldn't hurt to give VDIMM a healthy bump in BIOS, however, your DIMM slots may have developed a voltage instability due to a motherboard voltage regulator problem. Your idea of checking all DIMM's with Memtest in another system would be a solid troubleshooting step. Also, check all supply voltages with a DVM to rule out a PSU problem.