Power Supply Issue

[Ademia]

Recently built a new computer and it wouldn't start up. Tested each of the components in another computer of mine and they checked out properly. I put a different power supply into the new computer and it finally worked. I put what I thought was the bad power supply into a different computer and that worked too. I am lost as to why as the previous power supply has the right specs for the build.

Why is it that a power supply might work in one computer, but not another?

Thanks

 

[kajabla]

You probably didn't set up the first one correctly, missed a crucial plug or something.
More specs would be nice, though.

 

[venjhammet]

What are the specs of your PSU and PCs?

 

[Ademia]

the pc as a whole is made up of spare parts from previous rebuilds to a different pc(PC2 from which the now working psu was pulled from)

PC1:
BIOSTAR N68S AM2+/AM3 NVIDIA MCP68S Micro ATX mobo
AMD Sempron 140 Sargas 2.7GHz
HIS Radeon HD 4670 1GB
G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800

Tried two psu's in PC1 and neither worked:
Sunbeam 480W ATX12V Power Supply
Okia 450w ATX Power Supply

the psu that finally worked was pulled from PC2:
hec 585W ATX12V Power Supply

PC2:
ASUS M4N68T-M V2 AM3 7025/nForce 630a Micro ATX mobo
AMD Athlon II X3 450 Rana 3.2GHz
SAPPHIRE Radeon HD 5670
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM 1600

Oddly enough however the Okia psu is working in this system just fine(have yet to test the sunbeam).