Won't power on?

[JJRuhle]

I am having a small problem. My computer will not power on. It was working perfectly last night, and now will not respond. I put it into "standby" last ight after finishing with it, and went to bed.

This morning, the sleep button on my keyboard would not revive it, the power button would not work, the reset button would not work, and even unplugging the power supply for a few seconds and plugging it back in would not work.

I am thinking that this is some sort of a power supply problem, but in my experience, they do not just go bad instantly, they take a while and often cause your computer to restart unexpectedly.

Does anyone have any ideas on how to fix this thing or properly diagnose it?

Thanks!
~Jeff~

 

[wolluf]

Power supplies unfortunately do sometimes just die. First thing I'd try is resetting the CMOS - usually a jumper on the motherboard will do this. Then if no good, I'd try another PSU (I'm assuming you checked all connectors on mobo - so its not something simple like the 2 pin power connector connector come loose).

 

[wolluf]

PS. Is there any sign of power getting to the board - eg, some boards have one or more lights which are on when the power is connected. If not, have you checked the fuse in the plug?

 

[edfair]

Oh, they go out like incandescent bulbs most of the time. Working fine one second, then gone.
But this can also be the M/B if this is ATX. They depend on a low voltage circuit to be working on the M/B to enable the rest of the power to come up when you depress the power up button on the case.
You might get some indication if you unplug the power for a couple of minutes then plug it back in. If the main supply is good the fan may jump for part of a rotation until the M/B power down circuits get control and shut it off.
You could do a sniff test at the exhaust port for the power supply fan. There may be a distinct burned odor if something inside overheated when it went out.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[JJRuhle]

I see no light coming from the board indicating that power is gettnig to it, but I do not know if there originally was one. I am currently digging through mannuals trying to find out. I will check the fuse right now, hadn't thought of that. Thanks!

 

[JJRuhle]

Ed,

The motherboard is ATX. I tried unplugging the PSU, and then plugging it back in, immediately hitting the power button afterwards. I got no lights from the motherboard (although from the manual, it sounds like it will only give me light when it is on or in standby) and no movement of the PSU fans. I feel like it is a pretty safe bet that the PSU is a gone. I ordered a new one from NewEgg, since they have a fairly liberal return policy if this is not the problem.

Thanks!
~Jeff~

 

[JJRuhle]

Well, I got the new PSU today, and installed it. There is a green LED on the motherboard that now turns on, which is a good sign, because it means that the old PSU was dead. However, the computer sill still not power on. Pressing the power button, or shorting the little jumpers does nothing. No fans start, no lights or LEDs blink, what could be the problem?

 

[wahnula]

Hmmmm...could be the same old story...PSU goes bad and takes the MB, CPU or cards with it. Make double-sure the connection is correct, the PSU is switched to "ON" and the 110-220 slider is in the correct position.

 

[JJRuhle]

Yep.... All that stuff is checked.

It must be the motherboard that is bad, because I am pretty sure it would take me at least to the BIOS even if the CPU weren't working, and it won't even power on...

I guess I will have to try replacing the motherboard and/or CPU....

 

[ChillLead]

Did you use thermal grease when you installed the fan on the cpu? it not, the cpu may be overheating triggering the auto shutoff to avoid overheating.

 

[JJRuhle]

Yea... I used plenty of thermal grease. I had been running the computer for about a year with no problems.

However, I was up in Maine at school, where it is generally a lot cooler, so I have the PSU fans turned way down, and when I came home to NJ, I never turned them up. So I think the PSU just overheated, failed, and took the motherboard and/or CPU with it.

 

[kmcferrin]

I am pretty sure it would take me at least to the BIOS even if the CPU weren't working,

Actually, it probably wouldn't. The BIOS ROM chips include code that is read and processed by the CPU on bootup. If the CPU is dead then the code stored in the BIOS chip can't be read or processed, and so you will get no display.

I'm only saying that so that you don't rule it out prematurely.

At this point I would try stripping it down to the bare basics: CPU, video card, and 1 stick of RAM to see what you get. Also, make sure that ALL of the power connectors from the PSU to the mainboard are connected. It's easy to forget the 4-pin connector sometimes.