Failure to boot

[Garee]

I woke up to find that my PC will not start up properly. Here is what I have gathered so far:

When I press the power button both the CPU cooler fan and the PSU fan turn on for 5-6 seconds before power to both stops completely and everything turns off.

I removed all peripherals/hard-drive etc so that only the CPU,Mobo,PSU and RAM was left. The issue continued. I tried each stick of RAM seperately and the still had the same problem.

The only time something new happens was when I disconnected the CPU power cable from the mobo. This time both fans stayed on as if the system was starting up correctly.

I have no idea what is causing the problem however I suspect it may be the PSU or the mobo is dead. I checked for short circuits however I could not find one and there is no LED on the mobo that I could see either.

I do not have any spare components like a PSU to test with.

Any help would be great, Thanks.

 

[Ritwik7]

Was this PC working fine before or is it a new rig?

The best bet under such circumastances is to borrow a known working PSU and test with that first. Or use your current PSU on a friend's PC to see if it is working.

 

[Garee]

The system has worked fine for 2 years. However recently it would shut down automatically when I tried to start the game football manager 10, otherwise it was fine.

 

[mailpup]

See what happens if you switch off the power supply at the back or if it doesn't have a switch, unplug it for 10-15 seconds, switch it back on and then try to restart the PC.

 

[BlackIrish]

Had the exact same problem (fans powered on for a few seconds), it was a dead PSU - get a new one, probably with a few more watts.

The same thing can happen with an overheated CPU, though this shouldn't be the issue as your computer didn't power on from a cold start.

 

[seanc]

I second the failed PSU option.

Capacitors have most likely degraded/failed.

 

[TheWingNut]

I would suspect a bad PSU also.

 

[EpicPie]

What are your current system specs? Including the wattage of your PSU.

 

[Garee]

240W PSU
Q6600 @ 2.4Ghz
4GB DDR2 533Mhz
320GB HD

 

[seanc]

That PSU is not powerful enough.

You need something of at least 400w, you haven't factored in your graphics card either!

 

[EpicPie]

240W PSU
Q6600 @ 2.4Ghz
4GB DDR2 533Mhz
320GB HD

I would suggest 500 watt PSU minimum for a Quad Core CPU, the Q6600 can takes up 120 watts on full load on the factory speed. If you plan to over clock you need a bigger power supply fo sho and that 240 watts you already have isn't going to be enough for your system to get enough power.

 

[Garee]

That PSU is not powerful enough.

You need something of at least 400w, you haven't factored in your graphics card either!

The PSU and my system has worked fine for 2 years and I do not have a graphics card.

 

[seanc]

That's fair enough but it sounds like it has reached the end of it's life.

 

[Garee]

I replaced the power supply with a 400w Corsair - The same thing happens. Fans come on for a couple of seconds then it dies. Now I am thinking it must be the mobo or cpu...

 

[Ritwik7]

Now it becomes an expensive decision if you can't determine whether it's the motherboard or the CPU. Is there any one you know on whose system you could try out your processor?

 

[seanc]

Does it power on with the 4 pin P4 connector unplugged?

If it does, dead CPU or shorted vcore.

 

[Garee]

Does it power on with the 4 pin P4 connector unplugged?

If it does, dead CPU or shorted vcore.

Yes when I disconnect the 4 pin cpu power cable and turn it on the fans stay on as if the system has started up properly.

 

[seanc]

What motherboard do you have?

Can you take torch and look around your CPU - might be a good idea to remove the heatsink (don't power the machine up with it removed!).

Look for any burnt/damaged chips and blown capacitors. Capacitors should be flat on the top and standing flat. If the tops are bulging, have orange crusty stuff on top they've failed.
Note, bad caps can look normal.

You'd be wise to test your CPU in another motherboard if possible, this will confirm your CPU works. I would advise this as if you have a faulty board, you don't want to damage someone elses CPU.

 

[Garee]

I had a look and could not see any abnormalities. Also, there are no beeps coming from the mobo - would this mean the mobo is at fault? I thought the mobo was supposed to beep if there was a problem with the cpu.

 

[Ritwik7]

You'd be wise to test your CPU in another motherboard if possible, this will confirm your CPU works. I would advise this as if you have a faulty board, you don't want to damage someone elses CPU.

I'll second that opnion.

 

[seanc]

A motherboard will produce no beeps without a working CPU, which is your scenario.
You either have a faulty CPU or a fault in the power circuitry to the CPU, possibly even a faulty socket.