40MHz Daystar Turbo 040i Speedup
The Daystar Turbo 040i 40MHz card in a Mac IIci and IIsi can only be clock chipped to about 42MHz with no loss in stability. Take a look at the 33MHz Daystar Turbo 040i Speedup file for more info. The card comes with a full size metal can 20MHz oscillator, and that can be replaced with a socket so you can try different speeds. At 44MHz and above there are problems with 800k floppy disks. If you don't use 800k floppies, then 48MHz works fine. The 1.44M floppies are fine in all cases. At 50MHz (with a 25.2627MHz oscillator) the floppy drive no longer works even with the 1.44M floppies.
The latest version of the Turbo 040 software is QuadControl Cdev v2.3