what to replace an old tnt m64 8MB agp card

My friend had an old compaq comp given to him. It has a tnt2 M64 card
in it. i have an old tnt2 ultra laying around doing nothing and was
wondering if i could replace it. ia m worried about different voltage
issues. AGP 1X vs 4X etc.

I'd hate to damage his comp by putting my card in it. The card I want
to give him is a Diamond Viper V770 tnt2 ultra. It's a AGP 2X card i
think, and I remember my Gigabyte motherboard manual said to set the
jumper because it would be wrong voltage. At the time i replaced it
with a Radeon 9700 pro, so i didn;t do anything with it, it went in a
drawer.

I also have a Dell Geforce2 gts pro, but my mom is using it in her
machine now.