Took all day to download Mass Effect through Steam, finally get to play it and about 20 mins in (after messing with resolution etc.) the screen goes black and the PC looks like it has reset.

Monitor light goes to amber (standby) and the DVD drive light is flashing so I press the eject button thinking it's trying to boot from a DVD. Tray comes halfway out (no DVD in there) and then all the power goes off.

Press the power button on the front of the PC and it goes to startup for 2-3 secs, no beeps, and the shuts down and then starts up - over and over. Have to switch off at the PSU switch to stop it.

I opened the case up and change out the 3D card - same thing. Remove 1 stick of RAM - same thing. It was midnight at this point so I left it.

I am thinking it may be a PSU issue. I initially thought it was the 3D card as I had problems previously, but there were no graphical anomalies before it happened and a change of graphics card resulted in the same outcome.

I am going to try a spare PSU tonight and then if still the same try a bare boot with just the mobo, CPU, RAM and 3D card connected. Thing is it's a 650W Corsair PSU and only a year old and connected to 1 hard drive, 1 DVD combi drive, 2 sticks of 1Gb RAM, GeForce 9800GTX+ and has been fine for over a year. That PSU should be fine with that setup, right?

Never had a PSU go on me, is it likely to be that from what I have described? Any ideas?

Cheers

Wattage is plenty, brand name PSU - either that or the Mobo bought it. How old is the Motherboard?

It's about 1 1/2 years old I think. It's a Gigabyte 965P-DS3. The 3D card fan starts spinning straight away and then as the CPU one is just making a quarter turn it switches off.

Just read on the Corsair helpdesk to do the paperclip test. Make a U shape from a paperclip and stick one end into the green wire part of the 24 pin ATX connector and another into the black wire part whilst it's plaugged in and live! If the fan doesn't spin it's bad...

If I blow up it's good I guess lol.

Make sure the CPU fan is seated over the CPU correctly. If the vibration over time has worked the fan loose (away slightly from the MB) the PC will sometimes do what you describe.

It happened to me not so long ago - something to look at anyway.

I have just checked and the PSU is 1 year old on the 5 November!! I better get it tested.

The RAM, mobo and CPU were all bought in March 2007.

Buccaneer has a good point, it could be self-protection shutdown from an overheating CPU. The Mobo should be well within it's lifespan.

Just been home on my lunchbreak and tried to do that PSU test and there were about 6 black wires!! I picked the one furthest from the green but nothing happened. Anyone know which one I should use?

My other PSU has a smaller main power connector, might be a 22 pin? This won't go into the connector on my mobo...bugger!

I looked at the CPU fan and it seemed to be seated ok or are you saying I should remove and re-seat it? Hope not as it's an Intel one and is a real pain to get on.

Can you get into the BIOS menu? Is the date/time correct? If not, check the battery to make sure it's seated well, could be dead, but it should last a lot longer than 2-3 years.

I am going to have to take to a PC repair shop as I cannot test the other parts as I don't have them. It's £10 for just testing the PSU (which I was just going to take) or £30 for the whole PC... I am sure I had anther PSU with this mobo though as I had to upgrade to the Corsair because I bought the 9800GTX+, will have to have a search first. Hope it is the PSU as it will be in the manufacturers warranty still.

It could be the PSU, THE Reset/Power Switches or Pins, The CPU Temps, or something loose on the mainboard causing a power flux.

1. Disconnect the PSU Cables.. Check them for loose wires
2. Remove Heatsink fana nd re-seat.
3. Check Power/Standby and Reset switch pins on the mainboard
4. Check for loose hardware or connectors.