Opinions as to potential mobo fault in new machine?

[[k]ar|]

I'm in the process of building a new PC at the moment. Here are the specs:

Asus A8N-SLI Premium
AMD Athlon FX57
2 x 1Gb Crucial Ballistix
2 x BFG GeForce 7800GTX-OC
SoundBlaster X-Fi Elite Pro
2 x 74Gb WD Raptor Enterprise
300Gb Maxtor Maxline3
Asus DVD-ROM & dual-layer DVD-RAM drives
500w Enermax PSU

I've been testing this rig for the last couple of months - has been working pretty well, and I have been getting some fairly decent memory and HTT overclocks, all whilst testing WinXP Pro 64-bit.

I've had to leave the machine for about a month and came back to it this morning to do some more work on it - I was going to install the 32-bit version of XP Pro, then connect up my Vapochill LS phase-change cooler and a watercooling loop for the graphics cards. However, whilst starting the machine up, intending to begin by installing Windows, it fired up for a few minutes, then spontaneously shut down. Attempts to restart had the machine firing up for about one second before almost immediately powering down again. Bizarrely, after a while, it fired up again for a few mintes some time later, during my attempts at a diagnosis - again, it spontaneously shut down, and all further attempts to start have resulted in the same almost instantaneous shutdown. There's no time for anything to overheat, no time for a POST-fail beep code, not even enough time for the fans to reach full speed. It literally powers up them immediately shuts down in less than a second. Everything is still on stock cooling, and not overclocked at the time.

I've tried everything I can think of, but nothing has helped...

-new 600w PSU (insufficient power or original may have blown)
-hardware CMOS reset (bad BIOS setting)
-removal of all components from the mobo except the cpu (bad component)
-removal of the mobo from the case (something shorting)

I think my mobo has died. Any second opinions as to further investigations I can undertake?

[k]



>> Edited by [k]ar| on Saturday 22 October 21:37

[aldi]

Is the CPU fan connected properly? (it'l shut down if it doesnt register a decent fan speed after a second or two) Does it work if you take it out of the case completely and fire it up on the bench? (prefereably a non-conductive bench

[[k]ar|]

I tried it on a bench - no change. I also tried taking the CPU out of the mobo but leaving the HDD and CPU fan connected - the mobo kept running (the fans & drives span up and kept going) so my best guess is that something has gone wrong with the cpu.

I've requested an RMA on both the mobo and the cpu to be sure. I have to say I'm a bit puzzled as I can't think of any reason that this has happened. It was fine the last time I used it; I left it for a few weeks, came back and this fault occurred. Weird.

[k]

[mcflurry]

Maybe the overclocking killed the cpu?

[[k]ar|]

I don't think it is anything connected with that, as I dropped the CPU multiplier whilst increasing the HTT speed, so the chip was never running above it's rated clock - in fact at most times it was well underclocked, as I wanted to take the CPU out of the equation whilst seeing how high the RAM would go. I never got as far as OC'ing the processor.

Also, the first time the machine exhibited the problem, it had been running back at stock settings for a while. I could understand it if the failure had occurred whilst the chip was running out of spec or immediately afterwards, but to have gone wrong without having done so seems bizarre.

[k]



>> Edited by [k]ar| on Sunday 23 October 17:19