pc problem - motherboard related

[timl]

Hi, I am building a PC with the following parts:

mobo – Gigabyte H61M-USB3-B3 Rev2.0
CPU – Intel G540 G540 Celeron Processor, 2.5GHz, LGA1155, Dual Core, 2 Threads, 2MB Cache, Integrated Graphics
RAM – 2*4GB DDR3-1333
PSU – Thermaltake LitePower 600W
HDD – Seagate ST2000DM001 2TB Barracuda, 7200RPM, SATA3, 6GB/S, 3.5", 64MB

When I switch on power both the system fan and the CPU fan start up for 5 seconds and stop again. After a few more seconds they start and stop again. This carries on for some time.

I figured this could be the motherboard regulating use of the fan so I plugged the PC into a screen. Not a peep out of the screen. I left the screen attached for 60s.

I have 2 RAM sticks which I have swapped around and tried one stick only. I was expecting the mobo to beep when I powered on with no RAM but nothing there.

I have connected the main 24 pin power socket from the PSU to the mobo. Also the 4 pin 12v ATX socket. The power switch from the case is connected to the correct position on the mobo. CPU fan & systems fan are connected to the mobo. PSU connections to DVD and HDDs. Both connected to the mobo.

I received a suggestion that the 24 pin power socket is not properly connected. Specifically the 4 pin component of this cable. The labels on the PSU are sufficient to make this idiot proof and in fact the cable can only connect one way. Still, when I remove the 4 pin plug the behaviour of the PC is exactly the same as when it is connected.

Help!

[TheITGuy]

Hi, I had much the same happen to me recently - turned out to be a fault with the PSU. Might be worth trying an alternative PSU if you have one handy

[timl]

turned out the mobo was stuffed. It was an electrical problem and my guess is that somewhere the signals are being shorted but I couldn't see anything untoward. I tried 2 PSUs and 2 cases. Dropped another mobo in the first case and all was good

That's what ya get for leaving your new mobo in the box for 6 months I guess