Motherboard won't power up

[Pipear]

I have tried a few PSU's with some motherboards and found them not to power up the motherboard. If I change motherboards or swap around the PSU's they will powerup.
Any one any ideas?? This will leave me with one PSU and motherboard that will not powerup. Help please

[LazMan]

Ya gotta be a bit more specific. Name the manufacturers and models of the problem children. I don't recall having a Power Supply not energizing my bunnies unless there was that terrible burning smell oozing from the fan or lightning did the nasty. OK, I'm being fasticious.

I've run into OEM machines right out of the box that wouldn't power up that had burn-in stickers on them. It's not unusual to have a PS that suddenly decides it can't handle a load. Especially these days with all switching stuff and fancy gadgetry (oh how the days of the simple Heathkit PowerSupply have gone so far into the distant past... I even made a SUPER DUPER PS for my Commodore VIC20, back in those days of yore), it can be a simple broken or bent pin inside the connector or socket or it can be that there is nothing coming out of the power supply at all, even if the fan is running. If you have access to a multimeter, or know a friendly elecronic technician (or a wannabe) with one, you can check to see if the output of the power supply is what it should be. The specs for the power supplies are quite standard as to what voltage should be on what pin - whether it is AT or ATX (most motherboards have the PS requirement pinouts documented in the user manual).

If you're thinking the Power Supply is questionable, check it's output - under a load (that means plugged into the MB). If the power supply has power when plugged in, then this is not the problem. If pluggin a different power supply to this same board results in the board working AND the first power supply's output voltages under a load checked OK, then the output needs to be checked at some point past the connector to see if there is a problem with the connector.

I've never heard of a particular brand power Supply not working with a particular brand motherboard. I'm assuming that you aren't making novice mistakes of trying fit a square peg in a round socket or putting connectors on backwards (on AT-style boards).

Take care, let us know how you progress with this issue /forum/smile.gif

Laz

Laz