I've a TXP4 with a K6-III+ @500 MHz, and it now has a 64 meg MX420. I picked up a 128 meg Radeon 9250, but the system won't POST with it installed (but the card works fine in another motherboard). Does it have too much memory for such an old board, or is it something else? I'd try an FX5200, but those only seem to be available with 128 megs or more. And I did reset the jumpers to 66 MHz to make sure that it wasn't the PCI bus being out of spec that was causing the problem, but that made no difference.