PSU dosent work...

[Kirie63]

So I have an PSU that is 1000 watts, has worked perfectly for 3 years, but when I bought new mobo, it dosen't work. It works on the older mobo but not the new msi z77 mpower. Does anybody know what the problem is?

 

[alvine]

make sure you plugged in 8 pin cpu power

 

[Kirie63]

Well, have tried every possible way :/

 

[TenPc]

You have to also connect the cables to the video card if one is in use.

When you state that the PSU does not work, does it actually turn on? Does the motherboard light show up? Is the ram still in their slots? Is the power switch turn on at the wall?

 

[jsc]

Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=youtube_gdata

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.