I tried the card on 4 different machines 7300, 8500, 9500, and 9600 before I happened to dig out the 8600 Mach 5. It shouldn't be a cache issue since the 7300 and 8500 don't have cache cards. I used to get machines that were too old to sell from a local used Mac store. At the time that was B&W G3s and older. Quite a lot of the 75-9600 machines had G3 cards and extras like 128mb RAM, SCSI cards, ATA cards, Video cards etc. A lot of stuff I passed on to a local school and it's students, mostly G3s. The one thing I kept was all the 128mb RAM from the 75-9600s. While I do have some 60ns 128mb RAM I sorted that out and keep it separate from the 50ns. In this case all the RAM I'm using is 50ns. All the machines I tried the Sonnet 450/1mb in already ran fine with slightly slower Sonnet G3 cards, mostly 400/1mb cards. I don't have any other cards faster than 400mhz though I do have some Powerlogic and XLR8 ZIF cards. I guess I could try a higher speed with one of them and see what happens.