PC boot problems

[mhl]

My son's PC has started giving boot-up problems.

Here are some of the outcomes of various reboots after changing what is connected to the PC.

With everything connected (2 monitors + various USB devices), all the fans go to 100% speed, but nothing is displayed, not even the BIOS.

With both monitors + Mouse and Keyboard, the PC sometimes does the same as above, or it shows the bios correctly (I can enter the bios with no problems), but after the BIOS screen, it hangs just before the Windows splash screen, (it does not go into a reboot cycle). Also, rarely, it will properly boot up, but will not detect the second monitor.

With my main monitor + all USB devices connected, it was booting fine, so I came to conclusion that it was something to do with the second monitor. When I tested the second monitor to be sure, it gave the first problem (no BIOS, fans 100% load), so I assumed this was the problem, however, when I went back to the primary monitor with all USB devices, which had booted up just minutes before, but it then caused the no BIOS, fans 100% problem!

Another thing just to add to the confusion, after leaving the computer off for a few hours, when I returned and switched it on (with both monitors and all USB devices connected) it booted up perfectly fine!! But, this morning, it has just been throwing up the problems as before.

Does this sound like a PSU problem or a motherboard problem?

My Specs are as follows:

CPU: i5 3570k
Mobo: Gigabyte GA-Z77-D3H
Video Card: Gigabyte 4gb GTX670
PSU: Corsair 600W
OS: Win 7 Home premium 64-bit

[photolady]

Check the motherboard for blown caps. This sounds like a blown cap problem, but could also be the PSU problem. Since PSU is the easiest to replace, try a different one.

[mhl]

Check the motherboard for blown caps. This sounds like a blown cap problem, but could also be the PSU problem. Since PSU is the easiest to replace, try a different one.

Thanks for the swift reply, I don't have a test PSU, but have tested this one, and all rails are good.
Looking at the Mobo, I can't see any faulty caps.

Having put it all back together again, I switch on and everything seems OK. So maybe something was not seated correctly, but if the fault comes back again, I think I will get a new PSU, and the Mobo is still under warranty.

[photolady]

You might want to check hard drive and memory also. Both of those tests are on the UBCD posted in my signature. If you don't know how to burn an .iso file to make the disk bootable, read the FAQs.

[Midknyte]

Also reseat the ram.

I agree with Photolady. If you can borrow a PSU, swap it out. I've had PSUs test ok on a voltmeter, but still fail when put into a system.

[mhl]

After the successful reboot yesterday the PC ran fine for the rest of the day. But this morning it first threw a new error - A disk read error occurred. So I tried booting from the UBCD - but it won't even do that, although I know that the CD is a good burn because I have checked it on another PC. In between times it once booted into Windows repair mode and tried unsuccessfully to reboot. It has also reached the "Starting Windows" screen a couple of times, but never gets as far as the four-colour logo. It almost seems to be giving a different error each time I try to boot.

EDIT: after having reseated the RAM, in the two slots for the second channel, it booted up as normal, except the second monitor was not detected. Does this suggest a motherboard fault, or something different?

[photolady]

When you burned the cd, and booted from the other computer, did you do that before windows starts or was the disk working through windows?

Is this computer set to boot from the cd/dvd drive? If not, make it do that other wise UBCD won't boot the computer.

[mhl]

When you burned the cd, and booted from the other computer, did you do that before windows starts or was the disk working through windows?

Is this computer set to boot from the cd/dvd drive? If not, make it do that other wise UBCD won't boot the computer.

Thanks for your reply, and sorry if I didn't explain clearly.

On my 'sick' PC, I have it set up to boot from CD. It was trying to boot from the UBCD, but it kept throwing up linux error messages.

I haven't tried rebooting the PC from the CD following the successful boot that I mentioned in my last post, after reseating the RAM.

I have now got the second monitor working after a successful reboot into windows.

But I am still baffled by the random faults, and I would really like to find the cause of them.

[mhl]

I'm pleased to say that reseating the RAM seems to have solved the problem.

Many thanks for the help!