Macpro2,1 help

Hello All,

I am a new user that really enjoys reading this forum. I think I have read more about Macpro's in the last 2 weeks than I have read anything in my entire life...period :)

Anyway, I now turn to you experts to see if there is anything I haven't tried to resolve my problem.

Here's the backstory - My work gave me working Macpro2,1 that was missing a HDD and video card. They used the video card for another macpro and they wiped the HDD due to company policy. Here are the specs:

Mac Pro "Eight Core" 3.0 (2,1)
Arch 64 bit
EFI Arch 32-bit
6GB Ram

I bought:

Diamond Radeon HD 4870 512 video card (used)
1TB sata HDD (new)

I have a Snow Leopard OEM disk and also a bootable USB drive with Snow Leopard.

I can't get the video to display at all even when boot from disk or USB drive. When starting up I get the apple start up sound but no video. I have dual 24" LG monitors but I have tried them as dual and each individually in each dvi port.

I will admit I am a fairly new Mac user that has lots of experience with PC's. I have a Mac G5 that I mess around with but I would really love to get this Intel Macpro working.

Any and all advice is greatly appreciated. :D

Tony