Please - advice needed - Dead MOBO or CPU?

[aspenleaf]

I just built an Athlon 64 system with a GAK8NS ultra 939 and a Winchester 3000+ (retail). All settings were stock, no o/c. It ran great for two days, let just stopped, as if somebody pulled the plug. I took out everything but the RAM, CPU and videocard, still dead. I tried the MOBO outside of the case on an antistatic pad, still dead. I checked the power supply (Antec True Power) in another computer and it is fine. I also tried a known good PSU (another Antec True Power 550) and it's still dead. There are no PSU fans starting, no RAM LED lit on the MOBO, just totally dead. I RMA'd the board and received a new one today. Still dead. If the CPU was dead, would the MOBO LED light up and the power supply fan come on (neither do), or would it just be totally dead? Could I have gotten a DOA MOBO? I don't have another board to try the CPU in. The RAM, videocard and all other items check out in another (XP) computer, so I know it has to be the CPU or MOBO.
Any help would be very much appreciated. Thanks.

 

[mechBgon]

Welcome to the Forums I would expect the mobo's power LED to come on whether the CPU is dead, alive, or completely absent. You might try that, in fact... remove the CPU from the socket and see if that changes the behavior at all. Normally, if you have an utterly bare motherboard and you hit the power switch on the case, the PSU's fans will spin up and remain running (and the mobo will let out a storm of beep codes, of course). Maybe Gigabyte sent you back your bum mobo unfixed. You might want to mark it somehow before sending it in again.

I know this is a dumb thing to ask when you obviously have a good grip on troubleshooting, but the board's ATX12V plug is hooked up, right?

 

[aspenleaf]

Indeed, the 20 pin ATX and the 4 pin power connectors are attached. I tried the board with no CPU, and still completely dead. The PSU works if I hook it up to a different MOBO (Abit KX7-333r). Also, I tried a different PSU with the Gigabyte board and it's still dead, but that PSU works with the Abit board. As long as the power connectors are hooked up to the Gigabyte board, there are no fans, not even on the PSU. If I jumper the green (to black) wire on the ATX connector, I get power, the PSU fan comes on and my 12v and 5v readings are correct measured through a Molex connector. The 3.3v readings are correct measured at an orange wire on the 20 pin connector.


When I RMA'd the board, it was for a refund, and Newegg cross-shipped a new board to me. I'm not certain whether the first board was bad, the CPU is bad, or the new bad is also bad, and the CPU is OK.

 

[Cheetah8799]

When you sent in the mobo for RMA, you probably have a record of the original serial number on the first board. Maybe in an email form or something. Compare that to the serial number on the new board to see if they in fact replaced it.

Based on your description, I'd go with the bad board idea. But it seems strange that you'd have 2 bad ones in a row. Only thing to do is test the CPU in another rig. Otherwise we are all just making guesses as to what is busted...