IIRC, PDS Accelerators characteristically need a driver to put the CPU to sleep and boot from Mac/Onboard ROM.

The only plug and play PDS accelerator in the batch I have is the CrescendoPB G3 in Beater, that one's a processor card replacement  .  .  .  simply works  .  .  .  simply fast. OS9 on that mangled road warrior of a 1400c/G3@466MHz rocks.