I have 2 computers with the following configurations:

PC1:
Mobo: GIGABYTE GA-K8N51GMF-9 939
Proc: AMD Athlon 64 X2 4200+ 2.2GHz
Vid Card: XFX PVT73GUGD3 GeForce 7600GT
Ram: 1.5gB on 2x512mB and 2x256mB Sticks
Sound Card: Onboard
Hard Drive: 2x Hitachi SATA 250gb (RAID STRIPE)
Optical Drive: DVD+/-RW

PC2:
Mobo: GIGABYTE GA-K8N51GMF-9 939
Proc: AMD Athlon 64 X2 4200+ 2.2GHz
Vid Card: Onboard
Ram: 1gB on 2x512mB
Sound Card: Onboard
Hard Drive: 1x Hitachi SATA 250gb
Optical Drive: CD-RW

You will note that they use the same mobo and processor. The problem I am having is finding power supplies that will work with these systems.

Sunbeam NUUO SUNNU550-US-SV ATX12V / EPS12V
This supply was purchased at the same time as these processors and it is the workhorse no matter what i throw at it it works it works with both of these systems

mushkin 550250 ATX12V / EPS12V 580W
This supply initially didn't work until I noticed that the sunbeam had a wire missing from the ATX connector, it was a white wire the -5V supply. I figured that if the sunbeam worked without this wire then this one should too, so I extracted the pin from the connector. and it worked for 6 months and has now died and I can't get it to come back. after it died I tried the sunbeam in the computer and it worked.
after it died the fans came on but no post. Sunbeam to the rescue.

Antec EarthWatts 430-Watt ATX
Tried this supply and fans come on but no post.

BFG 650-Watt ATX BFGR650PSU
Tried this supply and fans come on but no post.

Have tried a few other supplies with the same issue the fans come on but it doesn't post, a couple didn't come on at all.

After every supply I try the sunbeam and it works. I would just buy another one of that supply but sunbeam has discontinued that model (The SOBs).

The only thing I can conclude about the sunbeam supply is it has higher ratings on the 5v and the 3.3v busses although a couple i have used have as high or higher ratings. Every supply has also been tried in both systems with identical results in each system. Most tests have also been run just with the motherboard plugged in and no drives.

The mushkin supply is on RMA to newegg but cause it's been 6 months I can only get another one of that supply maybe I will just pop out the -5v pin again and it will work but in case it won't does anybody have any clue as to what might be happening with these systems.

~one confused Electrical Engineer

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