Hey folks, thanks for letting me use your forums.

Here is my situation; A few weeks ago, my USB mouse randomly stopped responding. This ususally occured right at start up, where it would never respond to begin with. Most of the time, I could reboot and have the mouse work again.

Then, more recently, I would shut the computer down, and not be able to turn it on (in other words, I hit the power button, and all I get is the click of the button...the computer doesn't respond).

I posted this in the PSU section, because that is my best guess to what is going on. My motherboard light is on, but the PSU is making a weird noise when just being plugged in.

The best I can describe this noise is a high pitched hissing...it sounds almost as if air is moving inside the PSU.

I don't mind replacing a part, but I want to make sure which one is the culprit. The only other thing that I could think of is the motherboard..

Does anyone know a good way to diagnose a motherboard or PSU failure if the computer can't even turn on?

Thanks again guys.

Hello Bravo86, welcome to PCHF.

From what your describing, your definately on the right track.

When you place your hand on the side of the power supply, does it feel too hot? Is the fan spinning at the back of the power supply? Are there any signs of dust build up in the PSU and on the CPU fan itself? Is the power supply giving you enough power for all of your components (eXtreme Power Supply Calculator v2.5 - click Go Lite and add up to 15% for Capacitor Aging).

Madmonkey, thank you for the response.

I thought about the possibility that there was too much hardware for the PSU, but then realized that this probably isn't the case. I removed a ram stick to be sure, and it still wouldn't start up.

The PSU in question is a 350W Antec PSU. This is a custom built computer that is running a 3.2GHz Pent IV CPU, Onboard Video and Sound, 1 hard drive, 512MB Ram, and a DVD Burner...it's a pretty basic computer (It's actually my dads.)

This is all that the computer does for me right now.

1. I take the black power cord and plug it into the PSU.

2. I hit the power switch on the back of the PSU.

3. The rear 120mm fan on the computer case does about 3 revolutions..why I don't know, but it tells me that power of some sort is getting to that fan.

4. The green motherboard light comes on.

5. The PSU begins to emit the hissing sound that reminds me of air being blown through a narrow straw.

6. ...that's it. The computer won't do anything else.

Thanks again for reading guys.

So basically, in order to get the PC running again, you need to take the power cord out of the back and then put it back in again?

Heh..I wish..

At this point, I can't even get the PC to turn on again. Pulling the cord and putting it back in makes the light on the motherboard go off and come back on, and it makes the 120mm fan revolve 3 times...that's it. I can't get it to turn on.

Also, like I said before, the PSU continues to make that weird hissing sound as long as it's plugged in.

I have seen that happen so many times, and in most cases, it did turn out to be the power supply. Since your not in a workshop environment, you don't have the luxury of testing different parts. I can't hear the same noise you hear, but this most likely to be fan failure. This is the most common problem with PSU's. The fan fails, the PSU overheats and then bye bye power supply!! Normally when any other component on the PSU fails, the PSU does not work at all.

But a loose connection or short on board can also cause the same problem. Have you tried removing all internal components, HDD's, CD-ROM's, expansion cards to see if you can you hear the usual beep when you switch your PC on? (even without a graphics card you will normally hear multiple beeps to indicate error). Also try to reseat memory, CPU as well as both molex connectors from the power supply.