Help: Pc won't stay on for more than a minute (approx.)

[803hart]

To start things off, my specs are as follows:

CPU: Intel Pentium-D 805 2.6GHz
MB: ASUS P5B Standard i965 Core 2
RAM: CORSAIR VS 1GB(2X512)DDR2 5400, 2 x Corsair DDR2 XMS 1Gb PC5400
GPU: Gecube HD 3850 512MB PCI-E
PSU: 480W XCLIO SCF/aPFC/PCIE (Old/Faulty)

600W OCZ StealthXstream II (New)

HDD: 160G Samsung SATA II 7200/8, 320G Samsung SATA II HD321KJ
Sound: Sound Blaster X-Fi XtremeGamer

The problem started about a week or so ago when my pc suddenly stopped working. I opened the case and a distinctive burning smell immediately drew my attention to the PSU. Prior to this I had been facing the "famous" CODE 10 USB error, of which in the end I had to resort to using a usb expansion card to bypass the error. I realised that the green motherboard led would light up when pluged into the socket, hence I tried to turn it on with the hope that maybe it was a false alarm, wasn't I wrong. The PSU emitted a short high-pitched sound before completely dying (i.e no more green led light on mb).

I bought a 600W OCZ StealthXstream II PSU as a replacement, which arrived today. With sheer excitement I installed the new unit and booted up the PC, which went through the normal procedure (usual beep when starting, nothing new). I went into the bios setup screen to check if all was in order, and before I could exit, the pc suddenly shut down without warning. I checked all connections and for sure they were all fully inserted. I tried troubleshooting by removing all PCI cards, RAM (leaving one stick), disconnecting HDDs/Floppy/DVD drives, clear CMOS, even used an old GPU (ATI x1600) I had lying around, still experience the same problem.

I have a feeling the motherboard is faulty, however I have no way of testing the CPU. Pls Help

[Aard]

i suspect the motherboard will have taken on for the team when the psu died. if it was the cpu i would expect the system not to post at all. it generally take something rare to kill a cpu. only reason for an instant shutdown is overtemp afaik so it could be worth checking all heatsink are contacting fully

[Steve A]

It could be shorting out, check that your mobo hasnt shifted at all and the screws are not touching the board its self, or there isnt a loose screw fitting under the board (the brass ones that the screws fix into). may not be this but it is something that i would check if you are scratching your head as to what it could be.

[Behemoth]

Like Steve has said it could be shorting out, I had an abit KR7A Raid motherboard do the above many years ago. Would turn on for a moment, then it would just shut down. Took me ages to workout the cause of the issue, which was a motherboard pillar that wasn't where it was supposed to be.

I've also had a similar issue with my current mobo which was resovled by me taking it all out the case and running it ghetto style on a wooden bench and then hoovering out my case before using it again.

However I really suspect your mobo has bought the farm in this case if your PSU decided it wanted to take up smoking.

[Rainmaker]

This happened in my fiancee's PC for several weeks. It'd just randomly cut off and do an instant shutdown for no apparent reason. I'd reseated everything, messed around and generally become very frustrated.

Then I finally decided to do the obvious and remove the mobo to have a look-see... I'd left an old cooler backplate behind the mobo which was slowly moving around as the PC was in use (fans on etc)... touching mobo contacts and shorting them on its travels down the case LOL Instant cure upon removal - even if I did feel like a complete plonker.

So yeah, as above make sure the mobo isn't shorting. Hopefully it's something that simple and it isn't dying thanks to the PSU.

[Frank E]

Is the CPU / GPU / chipset / ...cooling fans mounted correctly, the correct amount of heat transfer coumpound applied, heatsink fins free from dust?

[803hart]

... only reason for an instant shutdown is overtemp afaik so it could be worth checking all heatsink are contacting fully

With regards to the motherboard overheating, I noticed that it would instantly shutdown at around 38-40°C, CPU temp avg 50°C. All chassis fans are running, however the hardware monitor reports Chassis Fan 1 & 2 Speed as N/A.

VCORE = 1.240V
3.3V = 3.296V
5V = 5.094V
12V = 12.038V

It could be shorting out, check that your mobo hasnt shifted at all and the screws are not touching the board its self, or there isnt a loose screw fitting under the board (the brass ones that the screws fix into). may not be this but it is something that i would check if you are scratching your head as to what it could be.

I'll have a look to see whether all the brass fittings are secure, hopefully reseating the motherboard will fix the problem *fingers crossed*. I bought the motherboard from SCAN about 2 years ago. On the Asus website is states that "All ASUS motherboard purchased after November 1st, 1999 will carry 3 year warranty services...", in my case, am I covered for this problem?

[803hart]

Is the CPU / GPU / chipset / ...cooling fans mounted correctly, the correct amount of heat transfer coumpound applied, heatsink fins free from dust?

I took all components out of the case, cleaned it out, checked brass fittings (all secure), reseated the motherboard and applied new thermal compound to the cpu. With only CPU, GPU & 1 stick of RAM, the pc still shuts down without warning at around 38-40°C (Note: All fans running, HW Monitor displays Chassis 1 & 2 fan speed as N/A). Now this has me baffled, to a point whereby I have come to the conclusion that it's got to be the motherboard.

[Frank E]

What are your High Temp alarms and shut downn threshold set at in BIOS?
Possibly corrupt bios? Check the release notes for the version of BIOS you are using. Maybe reflash your BIOS with the current version?

Does it shut down when you perform any specific action?
I have a problem with the same thing; when left clicking on Start Menu and traversing up, PC powers off when I get up 2 or 3 positions on the start menu, when right clicking on item in task bar it sometimes powers off when I move up a few positions on an app menu. Doesn;t do this in safe mode though.