Sonnet Crescendo NuBus G3 Upgrade
The Sonnet Crescendo NuBus G3 upgrade series comes in four flavors; 250MHz/512k, 240-266MHz/1M, 300MHz/512k, and 300MHz/1M. The cards comes with a 8x fixed multiplier (7.5x for 40MHz buses). The intention is to run the 250 at 240MHz in a 30MHz bus machine like the 6100/60. Unless I am mistaken, this card should also work in a 33.33MHz bus machine to give a 267MHz machine, in a 36.67MHz bus machine to give a 293MHz machine, and in a 40MHz bus machine to give a 300MHz machine. As such it's clock chipped. I have not tried this yet as I don't have access to one, but the only problem I envision is with the backside cache.
Having not seen one of these cards yet, I don't know if it is straightforward to change the multiplier, but if one clock chips the base machine it will speed up the new G3 processor. I doubt one can go much past 40-42MHz for the bus, but that's a nice improvement if you are starting at the low end.
If anyone has played with one, feel free to drop me a line so I can put some info with the results here.