I've got an Athlon 1200 and when i came home tonight, my comptuer will boot up for about 5 seconds, then all the fans will shut down, but the power light on the computer blinks. nothing else. I got into it and found nothing out of the ordinary, but i'm trying to figure out if this is a power supply related problem or am i looking at a new mb & processor! please help.

Difficult to say what exactly this could be.... many variables. Best way is to eliminate as many variables as possible then proceed in a step by step process of elimination.

First of all make sure that the CPU fan is running. Many MB's have a fail safe that shuts them down if the CPU fan fails.

If you don't have a UPS you could have had a power failure that caused an improper shutdown. This can cause very strange things to happen. Shut down the PS with the main switch on the PS and then unplug the Power Cord for about 30 seconds. This will clear the memory of any corrupted data that may be retained. ATX PS's still supply voltage to the SDRAM\DDRAM even with the PS switch in the off position. If still no boot, cycle the PS switch on and off about 7 or 8 times. Some MB's, such as Abit, have a failsafe Bios that will intialise after about 7 failed boots. Scrambled video card drivers ( after a power failure ) can also cause the boot shutdown problem. A common occurance with VooDoo5's for example.

If you've got another known good PS that you can use then install that first of all to save yourself some grief.

If things still don't work then you're going to have to eliminate things one by one. Disconnect all USB devices if you have any and see if it boots. If not, then disconnect your CD-Rom, CD-RW, Sound Card, NIC Card, Modem IDE Drives and finally your IDE drives one at a time. Get it down to where you only have the CPU, Video Card and one stick of Ram installed. You might also have to have the Floppy installed, although this varies from MB to MB. Hopefully, somewhere along the line, the danged thing boots. Then you can start adding items one at a time till it fails....or not.

Could of course still be the CPU and\or MB but you can only find out by a logical system or testing and elimination. Wouldn't hurt to get a good digital volmeter as well. A $29.95 Radio Shack model should suffice.

Well, went to CompUSA (only thing open on sundays)and bought a new power supply this morning to give it a shot. (Before i left, i tried turning it on again after being unplugged all night, and got about 1/2 second of PS fan, followed by the light). I got home, installed the new power supply, ran just the cards, one stick of memory. It ran for about 10-15 seconds, then shut down. Same problem, unplugegd everything, tried it again. 5 secconds, then flashing light. Now, i'm leaning towards motherboard. The only thing i haven't done would be disconnecting all of the cards, and using the vid card/memory only. The other thing i found (i haven't really looked in my computer since i built it last year) was my CPU fan completely off, hanging by the wire with my heatsink dangling by one tab. Looks like somewhere along the line a tab broke, too. Of course, i don't think any processor damage could have occured because, as you said, everything' heat monitored. It would have shut it down in an instant if it overheated. Thanks a lot for your help.

BTW, i have an Asus MB.

"...CPU fan completely off, hanging by the wire with my heatsink dangling by one tab."

On the contrary, It is very likely your CPU has been destroyed. Athlon CPU's prior to the XP series had no thermal protection, and would self destruct in less than five seconds without a heatsink.

Hm. I don't know how long it could have been like that though, what originally caused everything was a power surge.

As Shelly said your CPU's dead. Sorry :-(. The boards only monitor fan RPM. If the heatsink falls off but the fan is still connected the MB thinks everything is just fine. Meanwhile your CPU just fried in about 5 to 7 seconds. :-( :-(

One small chance. Was the heat Sink Fan an OEM unit? That is, did it come with the CPU when you bought it? If so, AMD will probably warranty your CPU. They're pretty good about that. Even if it was an aftermarket HSF, if it was AMD approved. They may warranty it for you if you write them a polite letter. Worth a try.

Yes, it sure was. Everything came in the AMD box! I think that's a good idea, i'll write them a polite letter and see waht tehy think about it. Thanks.