Mobo or PSU?

A few weeks ago I picked up an Antec True Power Trio 650W PSU for my desktop (Asus P4P800, 3.0GHz P4, 512MB RAM, 74GB Raptor, 5200FX, Audigy SE, CD-ROM & DVD-RW) because the old PSU was toast. I also installed a new CPU cooler and 2 new case fans - 1 at the front to pull air in and the other blowing out at the back - in addition to the original. One was hooked up to the PWR FAN connector, the other to CHA FAN. IIRC the original case fan was daisy-chained to a hard drive power connector.

ANYway, I hooked the PSU up, double-checking everything, and when I turned it on things ran for a few seconds then just shut off. Didn't see or smell any smoke, the power LED on the mobo came on when I turned the PSU back on, but when I hit the case power button the fan LEDs would flicker once and that's it. Turn the PSU off and repeat and the same thing happened. It smelled burned, too, a lot like a starter solenoid when you've cranked for too long. So, out came the PSU and in went an older one I had. It's not an ATX so I couldn't power up the mobo itself but I could power up the fans. Turned it on and all the fans spun like normal, LEDs came on, you name it.

So, back to Best Buy I went, with the bad PSU, my tower, and mobo manual in the truck. Told them what happened and mentioned that I had the tower with me so they said to go ahead and bring it in and they'd take a look. The first thing they did as verify that the PSU I was returning was indeed bad. Hooked it to my PC, and nothing happened. Next, they grabbed one of theirs (not shelf stock) and hooked it up. Nothing happened, so they used another one of theirs and tried again. Still, nothing happened. "Bad mobo" was the diagnosis. Now, I couldn't see inside the case too well because the open side was facing away from me but later that night I realized I wasn't 100% certain the guy had hooked up the 4-pin ATX connector to the mobo.

Anyway, I decided I'd just return the PSU instead of exchange it and do some further testing of my own when I get a chance to head to a friend's house in NH - but now that I have home internet access again I've decided to ask around and find out whether the BB diagnosis was most likely correct. Should the power LED (PSU on) on the mobo come on even if the mobo's bad? How about the fans, if a non-ATX PSU is used? And if it is the mobo, what's a good but not too crazy expensive one to look for? Socket 478, would prefer one without onboard sound so I don't have potential clashes with the Audigy, and don't need PCI-E because later this year I'm planning to start building a new PC anyway. At that time the formerly dead but now resurrected desktop would probably become a Linux machine.

 

Most (if not all) mobo's come with integrated sound; just disable it in the BIOS to avoid conflicts. Yes- bad mobo's will light up the LED (it simply shows power is going to the mobo) and bad mobo's will also get the fans spinning (again- just shows that voltage is flowing). Look around for any capacitors that have bowed-out tops or even tops with crud leaking out- caps commonly blow when a PSU fails.... Anyway- it does sound like BB's diag was correct. BUT- I think their faulty PSU blew out your mobo. It may have been your old one, but I'm not a BB fan so I'd rather blame them You should be able to pick up a decent s478 mobo for around $60-$70 w/ an AGP slot and/or on board video. Like I said; most mobo's have built in sound and trying to find one w/o it may be a major PITA.... good luck!

hopperdave2000