[hamei]

As far as downclocking goes I have zero experience, but I'm pretty sure someone on nekochan crashed and burned trying it. On the other hand as long as the new (faster) PIMM is capable of running at the slower values in the PROM you might be ok. A number of people posted on nekochan asking why their newly installed 600mHz PIMM still showed up as a 500mHz in an hinv, and were able to successfully flash the new values post install.  So going from slower to faster might be recoverable after the fact.

You can downclock, it's the only way I know of to make a mainboard run with a slower cpu. But you have to remember to do it with the faster cpu installed, cuz if you ship the board to someone with a 600 and you've been running it at 800, it's an oops :-(  and you can't do it with no pimm or a slower one installed cuz it won't boot. Catch-22.

Not that I've ever done that, you understand, but that's what I hear ...