Midway Vegas hardware questions. new problem, help

i have a vegas setup. its showtime, and to my surprise i flipped the game select dip and its also got blitz 99.

anyway.

i bought a gauntlet dark legacy upgrade kit, intended for gauntlet legends. i figure what the hell, lemme try it on mine.

it doesnt work. :[ the kit included the harddrive, the security chip (U27) and the boot rom (U37)

i cant imagine why it wont work. theres only one other socketed ic, U44. the mame romset just has two roms, vegassio.bin and the game bin (and the harddrive image obviously.)

the little led display counts some numbers for a while and eventually gives an E.
nothing displays on the monitor.

ok so ive got a problem.

sometimes when i turn on the game, itll show the boot up screen just fine. but when the game loads i just get a black screen. sounds all there, and you can play it and everything, just nothing on screen. its not the monitor.

this can also happen after its already been on.

im assuming its a bad video card, or going bad, but i dunno where to find a replacement. i know its a voodoo 2 or banshee, but i doubt i can just use a pc one.

the you test in a pc monitor and HDTV? is pci or AGP
is possible to test the 3dfx video card in a pc???