Boot like this:
knoppix 2

Then do this:

Code:
cat /proc/pci 
cat /proc/interrupts 
dmesg | less
Look for any errors, take your time and read everything- there's alot of info to be gained there. At least write down anything that looks like an error.

I realize that it will be hard to post all of that info when you can't boot into a desktop environment. You could try to use lynx and see if you can get online.

Since a voodoo2 SLI is only activated when you start a game or a andvanced graphic application and it shows a correct boot/desktop image it shouldnt be a problem.
Perhaps it isn't always in use but it DOES still get an IRQ no matter what right? Yank that bad boy out and see if it helps. I have had some issues w/ more than one video card and Linux before- don't get me wrong they can certainly work together but it's at least worth a shot right?

Have you been booting with any cheat codes?