PC failure?

I'm currently trying to diagnose the fault in a computer that refuses to boot. Yesterday it kept resetting after about half an hours use and so I looked at temperatures. Nothing was out of the ordinary and also the temperature probes in the machine were showing normal readings. This system is over a year old and has been stable for the whole time I've had it so I'm very familiar with what everything should show.

Then I was thinking a software fault in the operating system but before I got round to running a system restore in xp the problem got worse. Upon restarting itself the machine wouldn't load windows. It got to the screen that displays the xp logo and the scrolling blue loading bar but then froze about 20 seconds later.

Now it won't even get that far, the monitor displays nothing when you power it on. Figuring it has to be a harware fault I've had a look around. Cables and coolers are all seated properly and nothing appears to have changed. The fans all start and I can hear the hard disks operating. As display seemed to be the problem I switched in another graphics card but no change (also tried alternate monitors but again no luck). Basically I'm down to thinking it's the motherboard that's broken, or more likely (I hope) that the hard disk boot sector has somehow become corrupted. I doubt it's the whole hard disk that's dead as I can hear operating type noises but I guess it could be totally dead.

Before I go and buy a new hard disk can anyone think of anything else I could do to determine the problem?

If it is the hard drive just unplug it and try and boot it. It would still post just won't do anything after.

Sounds more sinister though, probably the motherboard or RAM, tried just one stick, different slots etc..?

After I wrote that I had a similar thought. Also I get absolutely no beeps or indications from the motherboard that it is working. I'll try the ram now.

UPDATE: Hmmm, not promising. Tried it without the HDD and it won't post. Also tried just one stick of RAM and then a different stick but again no luck. Thanks for reminding me to check those though.

The PC sounds exactly the same as usual, i.e. the noises of all the fans and disks starting so I'm almost certain they are all still alive. I guess this leads me to the motherboard which is bad.

Any way I can test it? It clearly gets power as the ethernet port lights up when a cable is plugged in, that's the only indication I have that it's alive at the moment.

Clutching at straws here but have your tried a cmos reset?

Take the battery out as well as part of the reset and replace after an hour or so, then reboot.

Other possible culprit is the PSU - if you have a spare, try swapping that out.

I would also go with trying a different PS. Even if it is underpowered it will at least get the motherboard awake without any HD's plugged in. Broken PS and MB can have very similar symptoms but it easier to try an different PS than MB.

Good uck hopefully just a PS.

Poo

The original symptoms read exctly as they would be if you had a knackered or deteriorating power supply. My 4-year-old Tagan 520W failed in a very similar manner (taking one hard drive with it to the grave), and I only twigged when I attached it to my Dell GX280 - it refused to boot, with the status LED citing "power issue". I opened it up, and there were about 4 capacitors leaking and one medium-sized cap even had one leg completely oxidised into a brown clump.

Check voltages with Speedfan/HWMonitor or maybe in the BIOS.

I agree that PSU is a likely culprit. But these situations are why I like my IP35-Pro and previous Abit boards. The LED will show a code which is a great help in finding out what's causing the problem.

Note that PSUs can still cause fans to whirr and lights to come on but still be knackered, e.g. maybe just not enough power on the 12V rail to boot. What is your PSU & mobo anyway?

Thought I should update this with what I've done. I've taken everything out of the case and created a little test-bed type area. Got a multimeter and tested all the relevant things on the power supply. All the rails are fine and everything seems a-ok there. I've tried all the other components (asides the cpu) in another machine and they work fine which is good.

Basically the only thing that can be dodgy is the motherboard so I'm contacting ebuyer about a return as it's still inside the warranty period I think. I've not experienced this kind of fault with a motherboard before, I'm kind of puzzled as to what caused it. I'd not done anything to the machine recently and I can't think of anything that would have caused such a problem.

One final thing, for someone running a single VGA card is it worth getting the Asus P5Q-Pro over the Asus P5Q? Are there any advantages to the pro other than the extra pci-e 2.0 slot? I'm thinking overclocking might be more restricted on the P5Q? I can't find any reviews of it, only the more advanced boards so any answers would be welcomed.

There isn't any bid differences. Extra port here an there and the better chipset cooling so it should clock better. But then both should be capable of 1600MHz. The PRO may have an improved BIOS for overclocking though, that I'm not sure about.