According to the datasheet, the original memory is a 2-Bank SDRAM capable of 66 MHz. Unfortunately, unlike EDO, such expansion chips are relatively rare.

With these cards in particular, it's probably cheaper to get an 8MB one than upgrade a 4MB one. Though also they don't tend to speed up all that much, since the GPU itself is a bit slow for the higher res that require the extra RAM.

Original Rage II with that much memory won't be cheap. But if a somewhat similar experience is acceptable, Rage IIc would be.

Okay, thank you people. I got Matrox Millennium G450 for AGP slot, 32 MB. Screen resolution is so much better now.