I went to install my Voodoo 5500 AGP on an system I'm putting together for old games, and I have artifacts starting on the boot-up screen, so it's not a driver issue.  Shoot, I have a bunch of cool old games I like to play like System Shock 2,, Thief, and even Asheron's Call which is still going since 1999.  They look so much better on the Voodoo, I wish there was something I could do about the card.

check if you havent broken of some capacitors when you have installed the card to your pc..

Everything looks like it should.  I suspect you are right though, probably the capacitors are going bad internally somewhere on the card, since they haven't broken off.  Dangit, I'm tempted to try and find another one on E-bay.  I've really had the bug to build a retro gaming box lately, after going over all the new hardware out there for my main rig that I'm going to build.  I just thought it would be cool to have something state-of-the-art, late 90's nostalgia style hehe.

Test your card on another machine.
And... Maybe your PSU is not enough for V5 5500 ? Some cheap PSUs rated
as 235 or 250W but real max output is 110-160W  

Quoteprobably the capacitors are going bad internally somewhere

It's almost impossible - ñapacitors on STB cards are very good.
But if PSU  is ok and you can see artifacts right at bootup (bios screens
or there's artifacts in any text mode - then it can be damaged memory.  

Have you been doing any modding to the card itself? Perhaps it broke down during the time.

I have heard about a Voodoo 5 that broke down a few days after the modding. A Heatsink placed on the memory short circuited some pin's. It went bad after a few day's though..