I installed one of my 8800GTX's in my wife's computer. Everything runs fine no apparent problems other then when I power down the computer.
Just before it turns off I get sort of a screaching sound.
any ideas on what might be causing this?

the computer specs are
DFI lanparty NF4 socket 939
opteron 170 2.5GHz.
2 gig of GSkill
1 sata hard drive
1 DVD combo
3 x 120mm fans
OCZ gameXtreme 700watt PSU