My Motherboard wont run

[Jannick]

this is my first time building a pc, but i dont know where to connect the power switch.
i tried a lot of pins but i get no feedback.

its a dell precision t7400 and there is a 40pin connector with no layout info.
there is also a led on the motherboard wich is off.
the led should be on when there is power right?

please help me get my pc running

 

[GhislainG]

You need to provide more info. New motherboard in the Dell case or new case for the Dell motherboard?

 

[Jannick]

You need to provide more info. New motherboard in the Dell case or new case for the Dell motherboard?

its just the motherboard so i cant just follow the wires to the power button.
im trying to get it into a new case.

 

[GhislainG]

You need to use trial and error until you figure out which pins do what, but using that motherboard in a different case is a challenge. Use a DVM and check which pins were used on the Dell case.

 

[Jannick]

You need to use trial and error until you figure out which pins do what, but using that motherboard in a different case is a challenge. Use a DVM and check which pins were used on the Dell case.

i dont have the case thats why its so hard to get the right pins.
and what about the LED on the motherboard, does it have to be on when you connect the psu or when it boots?

 

[GhislainG]

I don't know if the LED should be on when the custom Dell PSU is connected, but did you connect both the 24 and the 20 pin power cables? I presume you bought the motherboard used because it's cheap? According to this thread (T5400), the power switch connects to pins 19 and 21: http://www.tomshardware.com/answers/id-2740385/dell-precision-t5400-pinout-cables-dell-jr004-10pin-dell-jn454-40pin.html You may also be interested in this thread if you plan on using a GPU that draws too much current: http://www.tomshardware.com/answers/id-2002806/dell-t5400-power-supply-pin-pin-socket-mod.html