computer/electronics question

[wee beastie]

about a week ago my comp popped and burned something.  The fans wouldn't power up, so I figured it was my power supply.  So, I got a new PS, put it in, and tried to fire it up.  The power would come on for a split second (LEDs light up, fans begin to turn), then it cuts out.  So, I figured something got fried in there somewhere.

So, I gutted the cpu case, and arranged all the pc parts on a piece of cardboard to inspect them.  They all looked fine.  So, in a last ditch effort, I attatched my old power supply and it WORKED (although the mainboard--for some reason--seems to be getting quite hot).  I always wanted to put a better system in my mame cab, so I took these guts and threw them in the mame machine.  When I did this, the setup wouldn't work again.  Then, I tried attatching an old cd rom drive to it (as my cab only had a hard drive), and it worked again.  Just to test things out, I tried the new power supply on it again, and it still won't work.  It will work with the old power supply.  

Anyone have any idea what's going on with this thing??

Any input is immensely appreciated

[wee beastie]

I thought you guys were electric gods??!!!

Some gods you are!  I'll bet if I was drowning you'd forsake me and throw me a lead life preserver  

[Sasquatch!]

(although the mainboard--for some reason--seems to be getting quite hot).

This bears more looking into and/or greater explanation.

[SirPoonga]

Is this your only computer?

[Dave_K.]

Your computer going off immediatly after powering up usually means you have a grounded short somwhere.  Pull out all your cards and drives and try powering up.  I once had this bad external scsi card that had one of the copper teeth lined up wrong and it bridged two connections when in the slot.  A bit of scotch tape fixed it.  I'm not saying this is your problem...but to troubleshoot try disconnecting EVERYTHING from the motherboard, until it powers up and stays up.  Then add one device back in at a time until the problem happens (powering down and then back up with the newly connected device of course!).
This should help narrow down the problem to a particular device.

BTW: with the board outside of the case, its is going to get hot.

[JQ]

I had a similar problem when I ordered a new motherboard and CPU a few months back.  Press the power button, the fans start turning, and then shuts its self off.  When I called tech support they told me it was probably a grounding issue with the case.  They had me pull the motherboard out of the case and set it on the box it came in to see if I could get it up and running.  No dice.

Turns out the CPU was the problem.  It was a goner.  And every time I turned the power on, I noticed that there was a slight burning smell from the CPU area.

If you have a socket CPU, you can pull it out and look on the under side to see if it has any scorching.  Mine was an AMD 1500+, and that's were it showed signs of burns.  Be sure that if you put it back in, or replace it, to use some fresh heat transfer compound between the CPU and heat sink.

Daniel

[Driath]

It also could be your motherboard... now here's the real stinker about motherboards dying.... they have a tendency when they die due to shorting, surges, ect to take out many of your other cards   ... first try what Dave_K suggested by pulling all those other cards out and try powering up with the bare necessities... then if you have another computer handy you should try and troubleshoot each part to find out what's really bad and what's still ok.

Good luck