Can't get HD 3650 AGP card to work

I have an ATI Radeon HD 3650 512MB AGP graphics card that I can’t get to work.
I believe it is a VisionTek ‘Silent’ (no fan, cooling fins and copper heat pipes). Purchased as ‘refurbished’

PC specs:
Motherboard: Mach Speed P4MSD-800D2
North Bridge VIA P4M800 Pro
South Bridge VIA VT8237R PLUS
Processor: Intel Pentium D 940/3.2 GHz
RAM: 1.5 GB PC2-4200
On-board graphics: VIA/SG3 UniChrome Pro IGP
PSU: 550W+
2 HDD:
Master 0: 250 GB (2 – 125 GB Partitions, 1-Partition with Win XP Home SP3, 1-Partition with Win 8 Consumer Preview)
Master 1: 400 GB (2-200GB Partitions)

Installed video card is an nVidia Geforce FX 5950 Ultra 256MB, running dual flat-screen monitors (Acer wide-screen 16:9 and Dell std 4:3)

I uninstalled all the nVidia display drivers, replaced the nVidia card with the ATI card. Plugged in power connector to card. Upon reboot, I have no video output from either the DVI connector or the VGA connector. I have VGA output from onboard graphics.

Device manager shows yellow alert next to “VGA compatible graphics card”
Says drivers need to be installed/updated. Attempted to install ATI drivers, with no success.

Tried several iterations of drivers:
The latest from ATI/AMD, the drivers/software from VisionTek and Omega drivers/software.
None would complete the Catalyst installation process. Nor would the drivers load.

Uninstalled the ATI card, installed the nVidia card. Restarted, reloaded nVidia drivers/software. Now, everything is working as it was before.

Tried the ATI card several times and cannot get it to work (no video output)

Does anybody have any ideas? Is the card DOA as purchased or do I have a hardware/software problem?

Any ideas would be appreciated, thx.