Is this one of those mobo where the AT power connector is not Keyed? Not quite sure what would happen if the power was connected wrong ( like 2 red wires in the center) but I am pretty sure it would be bad.

MaxWar wrote:

Not quite sure what would happen if the power was connected wrong ( like 2 red wires in the center) but I am pretty sure it would be bad.

I've done that several times in the past by accident (being in a hurry or careless) and fortunately the PSU just failed to start, it probably sees a short circuit and shuts down.

MaxWar wrote:

Is this one of those mobo where the AT power connector is not Keyed?

No idea what that means by AT power connector is not keyed? I just assumed the two blacks go in the middle as per normal. The board was working when I bought it (supposedly).

Normally there are little ''teeth' on the connector that prevents you from connecting power in reverse.
But apparently some mobo do not have them. I never saw one of those but I read about them.
Looking at the picture it was hard to see but I thought maybe yours did not have the ''teeth''.

MaxWar wrote:

Normally there are little ''teeth' on the connector that prevents you from connecting power in reverse.

Ah, nah definitely the power connectors only go in the "1D". Bad dad pun 😀

If the board or a component has an electrical short then it could overload the PSU and cause it to shut off. In theory the PSU shuts off in time to protect itself but I think it could hurt the PSU if it keeps happening. I remember a PSU I used to "abuse" for testing unknown motherboards, and after subjecting it to a few too many overloads the PSU finally popped like a firecracker one day.

You could check for shorts on the board with a multimeter on the power input pins. If you get very low resistance from any of the voltage rails to the Gnd pins (or to any other voltage rail) then there's a problem. On ATX motherboards the resistance between rails is normally in the thousands of ohms, I don't know if an older board would be much different.

shamino wrote:

You could check for shorts on the board with a multimeter on the power input pins. If you get very low resistance from any of the voltage rails to the Gnd pins (or to any other voltage rail) then there's a problem.

Thanks for this, I now need to get a multi meter, and then figure out which rails are the voltage rails 😜 I haven't used a multimeter in yearssssssssssssssss

I have no idea what happened, but just incase anyone comes across this thread, the motherboard just started working again. It's one of those weird things where it now boots each and everytime. Case closed!