Asus P6T SE / Core i7 920 - No Power

[ruu1989]

Reposting from overclock.net becuase I'm really starting to tear my hair out over this, and I've had great help from here in the past!

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This build is about 3 years old and has been absolutely rock solid until the last few weeks.
CPU: Core i7 920 @ 4.0GHz (1.275v) with aftermarket cooler Akasa (AK-921).
MB: Asus P6T SE
MEM: 3x2GB Kingston HyperX (roughly 1600mhz with overclock).
GPU: 2x Radeon HD 5850 CF (one sapphire, one asus).
PSU: Corsair GS800
CASE: Antec 1200 (it's beautiful!)

It's been running absolutely stable for almost as long as I've had it.

During long gaming sessions I was starting to get BSOD's. Checked temps and turned out the thing was running at 65-70c idle. Dropped OC back to stock in the BIOS, but temps were still high.

So yesterday I opened it up and gave it a good clean out (its first for about 14 months - thick dust caked on the cpu hsf fins). I lifted off the heatsink and put on a new layer of arctic silver. Put everything back together and pressed the power button - no power. Lights on USB devices on, little internal power switch LED is on, but nothing happens when anything is pressed.

I disconnected the mains power, reset the CMOS, and it booted fine. However, I then noted that BIOS and Windows only reported 4GB of RAM. I tested each stick in turn and they were fine, however, noted that the middle 'channel' didn't appear to be working. So for now I have ram in slots 2 and 6.

Spent last night watching a movie, playing F1 2012, no issues, no problems. 45c idle, and 60-70 under full load (prime95).

This morning, power button, no power. Reset CMOS, nothing. Removed all devices including usb and GPUs, nothing. Tested PSU with paper clip and it appears to be fine.

I have a bad feeling the motherboard is fried, but I'm open to suggestions.

HALP! (please!)

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Since I posted this (48 minutes ago), I've been sat reading some of the (really!) cool custom build logs using my GF's PC. Suddenly mine springs to life, with absolutely no intervention from me. Goes straight into BIOS. Can move around bios, change settings, etc, etc. Note that defaults are currently selected, but that's probably OK for now. Save and Exit - BIOS hangs. No response from reset switch, or power switch, just stuck with BIOS on screen. Have to turn off at PSU.

Now it won't boot again, same as before. Lights are on (mobo LED and USB LED's), but nobody is home.

What is going on?!

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Ok, so a little more information!

PC 'magically' started by itself again. This time, instead of hitting F2 to enter bios, I just hit F1 to load defaults and continue. I got as far as 'missing operating system' when I remembered I needed to set RAID in the BIOS.

Interesting note... At 'missing operating system' the reset switch did nothing, the power button did nothing, manually shorting either of them on the motherboard did nothing...

The only thing to turn it off was to turn off the rocker switch on the PSU.

Am I bashing my head against a brick wall here? Do I just need to accept the mobo is most likely dead?

If nothing else, I have a small (but not insignificant) amount of pictures I'd like to be able to recover from my RAID 0 system disk. Guess it's not the end of the world if this is lost.

Thanks,

 

[alexoiu]

Hi,
I suggest taking the board outside the case, removing the CPU and checking the CPU socket for bent pins and extra paste. If all's fine, clean the old one and repply. Then install the CPU and test the board outside the case with a minimum configuration.

 

[ruu1989]

Hi,
I suggest taking the board outside the case, removing the CPU and checking the CPU socket for bent pins and extra paste. If all's fine, clean the old one and repply. Then install the CPU and test the board outside the case with a minimum configuration.

Hi Alex, thanks for the suggestion. I've already done that today, but just in case, I've stripped the mobo and psu out of the case, lifted the CPU, checked pins (all looked OK), re-thermal pasted again (I'm going to run out!), set up on breadboard, and still nothing.

As before however, about 5 mins after I plug everything back in, the machine starts up by itself and goes straight to BIOS (I can move about in the bios and change settings / load OC profiles freely). As soon as I exit bios it hangs, and the power/reset buttons are unresponsive. Once I reset it using the PSU's rocker switch, it wont start again - that's the bit that I really don't understand.

Gargh!

 

[alexoiu]

Then maybe replacing the CMOS battery with a new one... or the BIOS chip (you can find one on ebay). If still the same... hard to say if it's the board or the CPU. Maybe a local shop can help.

 

[ruu1989]

Curiouser and curiouser. So I got home from work today on autopilot, sat down at the PC and pressed the power button... Full boot. Writing from the machine now. I'm not getting too excited, there must be an underlying issue somewhere that I can't ignore, but it is really odd that it would suddenly spring to life again.