Faulty PC, shuts down in 2 seconds

[ragdoll]

Can anyone out there help me?

The original problem i had was when switching the PC on the case fans would work but not the CPU fan it would move slightly then stop and keep on doing this, the PC would then after about 2 seconds switch itself off and do the same all over again until i switched it off at the back.

So i decided to test the power supply, i removed the main power plug only and installed my old 300W main plug

The PC started and kept running and also the CPU fan. great problem solved its the power supply or so i thought.

Rather than wait for a replacement part from komplett i decided to use a freinds power supply.

Before installing it i tested the main power socket, and yes it started up CPU fan ran.

I then fully installed the new power supply and guess what.

No it did not switch its self on and off within 2 seconds, this time just the CPU fan did not run, The same problem as before, it would try to spin then stop, and again try to spin and stop.

Now if i remove the two CPU 12v power plugs numbered 1 & 2. the CPU fan would run the moment the PC is switched on, if i switch it on when the CPU power supply plugs 1 & 2 are in then it does the same as before, tries to spin.

A final point to note with all this is if i leave the PC running the CPU fan will start to spin after about 40 seconds, the fan will keep gaining speed with each turn.

The PC then works ok with no problems I hope i have yet to switch it off and on again.

Advice please is the PC faulty, should the CPU fan start up stright away when switched on

The mainboard i have is a Gigabyte GA-965P-DQ6,P965 socket-775, ATX

Please help.

[unrealuniverse]

If you have the fan plugged into the motherboard then it really seems like a motherboard problem as it seems like the motherboard can ajust the power to the fan but it isn't supplying enough to get the fan going fast enough. If the CPU fan is plugged directly into the power supply then I have no idea what the problem is.

If you have a 4pin molex conector to a 3 pin fan connector then you could run the fan directly off the power supply. It would always run at maximum speed however it may solve your problem if your motherboard is no longer in warrentee.

I would advise you to get another opinion off someone else before you send the motherboard back though as it may just need a bios update.

[ultimate]

Possibly could be your cpu wants reseating by removing and cleaning of the old paste from the cpu and heatsink then renew with a decent thermal paste such as arctic silver or you have a faulty cpu fan.

[mistrip]

Yep, i'd try reseating the CPU, it could be overheating although the fact that it worked with your other 300W PSU suggests maybe not. Other than that did you use the spacers between the motherboard and case?

[peterb]

Are you tesing the power supplies before installing them in the case? Does the original power supply work if it isn't installed? If so it could be that there is a funny earth problem or a short somewhere from the mobo to the case.