Question about Desktop Power Supply Unit and MOBO

[dj-mdx2]

Hi, first post here so be gentle. I need some advice. I'm assembling a micro ATX desktop with my daughter for her birthday, and I must confess it's been 7 or 8 years since I've built a PC.

My situation is that I'm using a Matrox socket 478 MOBO with Intel Celeron 3.0 GHz plus the usual components for a basic setup. The case is an Aspire XQpack with a built-in 420 W Power Supply Unit or PSU from newegg (which has received some bad reviews because of the PSU) . I'm pretty sure all the components will not even total 300 W, so no chance of overtaxing the PSU. During the building process, I turned on the unit 3 times to make sure there was power, and the PSU fan and case fan, LEDs and HDD indicator all came on. Once the system was finished, unfortunately, to my and my daughter's disappointment, only the Power indicator light came on. There was also a burning smell from the PSU. I immediately turned it off.

I called newegg and though they could not replace just the PSU, they did give me partial credit and I ordered a Coolmaster 12 V ATX PSU with 2 built-in fans.

Well, today I put the new PSU in, made sure all connections were secure and again, only the Power indicator light came on. What's interesting is none of the PSU cooling fans came on. Unfortunately, I don't have a multitmeter or anything to test it with.

Does this mean my MOBO is fried? Or does this mean I received another bad PSU? In other words, do the cooling fans on newer PSUs come on if you power on just the PSU or do they work in series with the power to the MOBO and thus will not turn on if the MOBO is fried? I'd hate to disassemble everything and send components back and then wait for new parts to arrive. I may have to take the whole thing to a local computer shop to be tested.

Any help would be appreciated. Sorry for the longish post. I hope I can contribute my own advice down the road to other members.

[PardeGT]

Coolmaster is a pretty decent brand. It is possible the first PSU fried the motherboard. But before jumping to conclusions follow the instructions in the thread below and see if it is not possibly just a grounding issue first.

http://forum.pcmech.com/showthread.php?t=132409

[dj-mdx2]

Thanks! I did read all 6 pages of that thread before I posted. I haven't tried disassembling and reassembling yet - gotta free up some time. I was hoping somebody could tell me if the heatsink fan, PSU fan or case fan would work even if the MOBO is fried. Oh, and btw, on intial powerups, the LED light from the casefan would briefly light up. I hope this is just a grounding issue. Otherwise this project is going to turn out to be a Christmas gift instead of a birthday gift.