Can you provide a model number on the psu and a model number of the Asus board you have in the other 2 rigs?
Be right back, I will go check! They have the same thermaltake 750w bronze series PSU but I will get the model of the mobo for ya!
EDIT
Asus M4A79XTO EVO motherboard.
2 PCIe and 2 PCIe 1x -- so if you are brave you can put 4 cards on it.