Just don't install the rocket on a Nubus PPC....slows down the main mac. It's best on a Quadra 650/800. I haven't tried it on an 840AV, but it should work, and work well, with the 840AVs advanced Nubus system.

The 40Mhz Rockets were different beasts, called the "Stage II," and couldn't be used as accelerators, only as multi-macs.