Dell 5100 diemension - dead

[joydivision]

I thought it was the PSU but I have tested it and even tried it in another machine and it works perfectly.

The motherboard LED comes on but when I press the power button its completly dead.

So its either:-

Dead motherboard
Dead switch

Normaly I could just short the pins on the power header but being a dell all the case lights/button are on a ribbon cable and I have no idea what to short without stripping everything down and tracing the cable, even then its going to be very tricky to do.

Is their a simpler way I can force the PSU to power on with the main 24-pin header connected to the motherboard?

[Alan22]

The 5100 along with the E510 are notorious for having this problem. Browse the Dell forums - there are hundreds of posts discussing this. In fact, you may be overwhelmed with the sheer number of posts.

[Styxbound]

Jump the green and a ground to start it. A little risky to leave it plugged into the board though if there's a short. But you know how it is: no guts, no glory.