AGP Pro50 slot issues

Heres the issue, i have yet to figure out why this isnt working.

Current mobo i have is part of a server tower ive set up as a desktop. Fujitsu Siemens Celsius R610 if anyone wants a looksee

Note: Drivers are available for all of the following cards for Win Vista at the minimum, Win7 for the more recent ones, so theres no issue with finding drivers or compatibility

Originally the board had:

Quadro 4 980XGL 128 mb, the card started artifacting in windows 7 so i had it removed.

Matrox Millenium G450 32mb worked fine, so i left it, cept sister noticed that youtube videos stutter on it full screen, however HD movies or tvshows i have on the computer itself run fine full screen.

Geforce FX 5200 128mb, youtube works fine in all modes, HD content on hdds stutters when fullscreen or windowed.

Geforce 6800GT, computer will not POST although it powers on

Geforce 7800GS, computer will not POST although is powers on

ive come to believe its a power issue, i have already tried booting up the system with only the primary hdd and vid card hooked up to the power supply, same result

im at a bit of a loss, list of known compatible vid cards is on the link but i`ll post here anyway (great my keyboard is messed up right now too)

Is the issue with the AGPPro slot itself? the current FX5200 in there is reporting that its functioning at 8x, so im assuming its gona do that for the 6800 and 7800 as well :S

Professional 2D: Nvidia GeForce FX 5200 (64 MB, AGP 8x, 2 x DVI-I)
Multi monitor 2D: Matrox Millennium G450 (32 MB, AGP 4x, 2 x VGA or 1 x DVI-I)
Matrox Millennium G450 (32 MB, PCI, 1 x VGA and 1 x DVI-I)
Entry-level 3D: Nvidia Quadro4 580 XGL (64 MB, AGP 8x, 2 x VGA or 2 x DVI-D)
Mid-range 3D: Nvidia Quadro4 980 XGL (128 MB, AGP 8x, stereo, 2 x DVI-I)
Nvidia Quadro FX 1100 (128 MB, AGP 8x, stereo, 2 x DVI-I)
High-End 3D: Nvidia Quadro FX 3000 (256 MB, AGP 8x, stereo, 2 x DVI-I)

Any input is appreciated!