Is my PSU dead?

[chrestomanci]

My system (see "My System" specs on the left). won't turn on. When I press the power button nothing happens. There are no LEDs lit on the motherboard. The system got left on during a power cut, so there could have been a spike or such like.

I disconnected the power cord from the back of the PSU, and plugged it back into the PSU. When I did the PSU fan spun for a few seconds, and then stopped. I have confirmed that there is power in the mains lead. So far I have not removed the PSU from the system or attempted to test it in any other way.

Does anyone recognize these symptoms? is my PSU dead?

In theory I could test if it is the PSU and more or less all the other components by cannibalizing my wife's PC (Hers has the same model of motherboard and CPU), but that would be quite disruptive so if someone can suggest what is wrong, it would save a lot of time.

Thanks.

[watercooled]

You'll probably end up testing by swapping out the PSU in the end so save yourself the trouble and do it whenever you have the chance. I could be very wrong but the fan spinning up for a bit suggests to me it might be the motherboard but again you'd need to swap out the PSU to test it really.

[peterb]

There is normally an LED on the mobo (powered by the auxiliary 5V line) that illuminates when power is applied to the PSU, even though it is 'turned off. (This is the line that piowers the soft start switch that you normally press to power up the device). The brief fan spinning would be the PSU starting and then shutting down as part of its start up swequence.

However - bottom line is that it is difficult to tell (at long range) what the problem is. The symptoms you describe could occur if there is a short cct on the PSU output (or a faulty MOBO) but could equally well occur for a PSU fault.

MY money (just) is on the mobo but unless you have a multimeter (and possibly a dummy load) and have the knowledge/skill to do some diagnostic tests (monitoring the connected voltage during start up - load/no load voltages etc, it will be difficult to pin down the fault other than by swapping out components in turn.

[chrestomanci]

As it happens, I do have a PSU tester, as Scan where giving them away with every order about 5 years back. As you can imagine it is just a simple one that simulates the soft start button, and iluminates an LED for each voltage line, so I guess the next step is to take the PSU out and test it with that. I also have a multimeter (I used that to test the power cord, by confirming that there was 230V across the live pins).

Bad news if the Mobo has died. I was hoping to get away with just a new PSU.

Thanks for the tips.

[chrestomanci]

Hmm.

I pulled the PSU out and plugged it into the cheap PSU tester, and it started right away. According to the tester, all the rails have voltage on them, though my cheap analogue multimeter says that the 5V rail actually has 5.5V on it, so that is a slight cause for concern.

So it now looks like I need a new motherboard. Can any one recommend a uATX socket 775 board with 4 DDR-2 memory sockets. (enough for 8Gb of RAM) ?