PC won't load

Kido

I'm struggling with my PC. I've not used it in a few weeks, and now when I go to switch it on, it won't boot. It loads the Gigabyte motherboard welcome screen, but that's it. It then re-starts itself. It won't let me into the BIOS or anything. It just stays at the Motherboard welcome screen for a few minutes then re-starts itself.
Does anyone know what the problem might be, and how to go about fixing it. I've checked that there's nothing catching in the fan.

pcombo

you tried taking components out and reinserting them, reset the bios, maybe PSU is become faulty.

remove all usb cables and any other.

Kido

I've taken everything out but still no joy.

robmar0se

Can you confirm that you actually tried to enter the BIOS (usually F2 or DEL)? If this doesn't work then then as the last poster says, disconnect all you can (eg USB devices, cds/dvds, card readers, etc), I would try another PSU, lots of old ones lying around. If it has a separate graphics card try another. I would also try removing the front USB cables too.

I have a 8yr old PC here at present with a similar problem, did as I have just said above, in the end I had to conclude the mobo had died.

Kido

I've tried to enter the BIOS using DEL but it doesn't work.
I've disconnected all the CD drives and USB devices etc. I'll dismantle my brother's PC and try swapping the graphics cards. Sadly I can't swap the processors as they're different.
Guess I'm off to the computer shop tomorrow after work, once I've pulled the motherboard out.

robmar0se

Can you try yr brother's Power Supply?

Kido

I'll have a look and see what it's attached to. His PC is scarily complicated inside and he's not here to put it back together if I mess it up.

Figment

Can you hear the hard drive and CPU fans starting up? Any beeps while the splash screen is displayed?

You could try disconnecting the mains power supply, then remove the BIOS battery from the motherboard. Wait a minute then replace the battery, reconnect power and re-test. If it works you will have to reset the BIOS clock.

Kido

The HDD and CPU fans both start up ok. No beeps.

robmar0se

Do try Figments suggestion, even try a new cr2032 cmos battery?

Regarding the PSU, these are very simple to switch in and out. I am concerned that the power to the mainboad is not right, the PSU supplies 3 different voltages to the board whereas the supply to the fans is a standard 12v.

If you are worried about taking it out etc, then just mark the cables as you take them out. But before you start make sure the unit in yr bro's unit has the necessary plugs as below.

There are usually 4 screws to detach the unit from the case.

On most boards there are two cables attached to the mainboard; depending on the age of the psu/board there will be a 20/24 pin plug, and a square 4 pin plug (these can fit only one way round) - 20/24 plugs are interchangeable - the 24 variety has a detacheable 4 pin extension that may be added removed as required - it will have no effect for testing.

The plugs for the drives are interchangeable but will be either IDE (4 pin molex), or sata. Both are shaped so can only fit one way round. there maybe also a small 4 pin plug for floppy drives (if there is one).

Some high performance graphics cards use a separate 6 pin supply.

A full list of connectors may be found here; http://www.playtool.com/pages/psuconnectors/connectors.html