Computer ALMOST turns on... but won't ;)

Hey guys,

I took some scraps from some old computers and put together a little machine tonight.

I'm using an Asus A7VL-VM motherboard and I put everything in just right, but apparently I missed something. I've hooked up all the power and I finished putting the little connectors in for the power LED, power switch, etc. Then I pressed the power button and the PSU fan came on for a second or two, then it stopped. Then the computer wouldn't do anything the second time I pressed the button. No lights on the front of the case flashed, but there is an LED on the motherboard that lights up when I plug the PC into the wall. As far as I know, all of the components are working properly. I believe I have the power switch connector in correctly. I've looked through the motherboard manual and racked my brain for something obvious I may have overlooked. Any ideas?

Here's the system specs, even though I don't think it's necessary, it can't hurt:

AMD Athlon (around 900MHz) socket 462
384 MB PC100 memory
Asus A7VL-VM motherboard
8GB Western Digital hard drive
15GB Seagate hard drive
Aspire 250 watt PSU
and I'm trying to run Windows 2000.

 

I have had the same problem doing just what you are doing, try another power supply, 9 out of 10 times it worked. ed

 

I have another PSU out in the car, and I shall try it in the morning. I am really puzzled though, 'cause it seems if it was the PSU then the LED on the mobo wouldn't light up. I wish it'd just cooperate

 

I too had a similar problem a few months back.
Mine turned out to be a faulty mobo.....I was going to suggest the PSU right up until you said the mobo LED would not light up at times!
Unless your PSU is completely dead, it should still deliver enough voltage to light up the LED, therefore leading me to be more suspect of the mobo.

This ofcourse, is providing you have done all your homework regarding all other device compatability!

Regards......

 

The LED on the mobo comes on-- I don't believe I have the front LEDs hooked up. I believe that's why they don't come on. Heh.

Trying another PSU momentarily. I'll let you all know what happens.

 

Double check the power connector pins to make sure the positive and negative pins are in the proper place.

 

Turns out I don't have another PSU. I really don't think it's the PSU, though, because this PSU worked fine less than a month ago.

And as for the power pins... I've fiddled with them and I think I've tried them every way they'll go. I've got the motherboard manual, but the diagram is a little confusing. Do a Google search for the manual and look on page 35... You'll see what I mean.

It's really strange. The manual says that a green light on the motherboard (which is on when I plug the PC into the wall) means that PSU is still connected and is a reminder to unplug before working on the motherboard. This to me seems to indicate a working PSU.

It's so strange though--- The PSU fan whirrs for a few seconds, but nothing else in the computer ever moves, not even the CPU fan.

Estima8tor, if you could help me with a better diagram for the pins, that may help. I've done this 2-3 times before, so I don't know why I'm having a problem hooking it up now. I am going to try to get another PSU today and try that, too...

 

Oh, by the way, I've read somewhere before that you can use scissors to bypass the little plugs to turn on your PC? Something like that. I didn't try that because I didn't know if it was safe-- it sounds a little sketchy. What do you think?

 

Plug the PC in, make sure the power switch at the back is on - then go have a cofee or something - then try and boot it. I always have to do this if I've left my PC unplugged for any length of time and I always get exactly the symptoms you describe.

 

Tried that...

Tried a new PSU, too, but that didn't help. Any more ideas/suggestions??

 

I still got no clue as to what to do next

 

im not a big hardware kind of guy and cant offer much except that your obviously missing something! The processor is in working order and everything? Same with the Hard drives?

 

The RAM and hard drives both worked within the last 24 hours. The CPU and Motherboard worked about 6 months ago.. They've been wrapped in anti-static plastic and foam until yesterday. I don't know why they'd die while in the closet.

 

Similar problem happened after my 19yo was tinkering....turned out that the ram was not seated properly.

So pull that out and reseat it. Might work for you to.

 

The computer should still come on, even without RAM, shouldn't it? But I'll try it anyhow

 

edit

 

Use a logical process of elimination to diagnose your problem.
If you used componentry from old systems, anything is possible and random guesses will not help.

The first thing i would do is remove the system from the case, place it on a non-conductive surface, and disconnect all components from the motherboard with these exceptions

CPU (and heatsink/fan)
A single stick of memory
Video
Power supply
Power button
This tests two problems at once. They are the possibility of some peripheral preventing the system from powering up and the possibility of the motherboard shorting onto the case somehow,or even being faulty.

If it still fails to give any power up at all, find where the power button connects and short those two pins for a moment with anything conductive that you have on hand. A screwdriver, knife, coin, or anything metal will work. If the system spins up, you need a new power button, if not, you have now narrowed the list of suspects to what you have connected.

You can discount the PSU that you have already tested!
Do a visual inspection of the mobo, for things like scorch marks at the ATX connector, leaking or bulging capacitors etc.
If nothing out of the ordinary and they all look ok, test repeatedly, with each stick of memory individually in each slot (this means nine tests for three sticks of memory on a board with three slots!).
If the system eventually powers up, you've found good memory and that is probably your only drama.

If not you its very likely you have yourself a bad motherboard, CPU or combo of both. (f your video is not onboard, remove the card and test just to be sure).

If it does, put it back in the case and power up again. If no problems start adding your peripherals, one at a time, testing Power up each time till it stops again....then you have your culprit!

Regards...