Dell 8400 keeps killing hard drives

I have a Dell 8400 desktop that has killed 2 hard drive back to back, the original one and a a brand new one. The the two drives are not recognizable when connect to another computer. They both received power, I can hear and fell it spinning, but it will not read. Also they DONT click so I am not sure what type of damage they have.

I am trying to figure out what is wrong with my computer before I put another drive in it. My guess is that it is one of the following:

- Power supply unit (PSU), large amounts of voltage are spiking on the power rails.
- Could motherboard be causing it or have a faulty controller chip
- As simple as the cable I was using?
- Northbridge on motherboard might be damaged?

I pulled out the PSU (Dell Model N350-00) and tested the voltage with no load and these are my results:

P1 Power Connector
1. Orange = 3.30
2. Orange = 3.30
3. Ground
4. Red = 5.01
5. Ground
6. Red = 5.01
7. Ground
8. Grey = 5.0
9. Purple = 5.11
10. White = 12.10
11. White = 12.10
12. Orange = 3.30
13. Orange = 3.30
14. Blue = - 11.96
15. Ground
16. Green Power
17. Ground
18. Ground
19. Ground
20. Empty
21. Red = 5.01
22. Red = 5.01
23. Red = 5.01
24. Ground

Molex P9
1. Red = 5.01
2. White = 12.10

Molex P8
1. Red = 5.01
2. White = 12.09

Mini
1. Yellow = 12.09
2. Red = 5.01

Sata
White = 12.10
Red = 5.01
Orange = 3.30