Question HP z400 psu problem

[Back2DFuture]

I’ve a hp z400 workstation. I’ve been trying to make it into a budget gaming pc by picking up a seasonic 500w psu and a Radeon HD 7950 I was given for a low price by a friend. The psu I bought was new only opened but even after getting a 24 pin to 24 pin since it’s non proprietary PSU it still won’t boot up. When I click the power button on the pc the fan spins for a millisecond and the psu doesn’t even boot up. Straight after I get 3 loud beeps.

 

[Barty1884]

3 beeps would appear to be "CPU not detected":
https://support.hp.com/lt-en/document/c03599666

Suggests the board is adequately powered etc, but you have an issue elsewhere.

Did you change/do anything else, beyond the PSU from it working to not?

 

[kanewolf]

3 beeps would appear to be "CPU not detected":
https://support.hp.com/lt-en/document/c03599666

Suggests the board is adequately powered etc, but you have an issue elsewhere.

Did you change/do anything else, beyond the PSU from it working to not?

There is a 4 pin supplemental CPU power plug in addition to the main power plug. Be sure you have the 4 pin plugged in also.

 

[--SID--]

Which Seasonic 500w exactly?
Does the motherboard have 6 pin or 24 pin?

 

[Back2DFuture]

sorry for the late replies the power supply is a Seasonic 500w S12 III and the motherboard has a 24 pin. my power supply wasnt working with my motherboard and found out i had to get a 24 pin to 24 pin adapter but it still doesnt boot up. Also i had the 4 pin cpu plug plugged in

 

[Back2DFuture]

also @barty i meant to say 5 series of beeps not 3