>  I popped the 040/33 into the centris and it did not seem to notice the
> difference. Apple System profiler still reports the machine as being a
> centris 650 with a 25 mhz 040. Just for gigles I \zapped the pram which
> seemed to make no difference. It still boots into bsd without a problem.

The CPU doesn't know how to make itself run at any specific speed.
The speed rating it was given comes from how fast it could run when
it passed tests at the factory.

So now you have an 040 that _could_ run faster, but your centris only
knows to run it at the speed of the original centris CPU.

NOTE: I am not an expert on these Mac models. But if they did things
"normally" then I would expect the following to work for you:

Look in your centris and your other Mac (the one the 040/33 came from)
for small metal boxy "cans" in sockets near the CPU. These are called
"clock oscillators" and they tell the motherboard and the CPU what speed
the CPU should run at.

If you're lucky, the one from the faster Mac will also fit in the socket
of the centris; installing this into the centris will tell it to run faster.

IMPORTANT!! You can damage the oscillator if you plug it in wrong and
turn on the power. To avoid this, look in the centris FIRST. The centris
oscillator should have either a single squared corner or a black dot on
one corner, or both. When you move over the oscillator from the faster
Mac, make sure it is oriented so that its squared corner or black dot
goes in the same direction.

If you can find a FAQ on the net, use that instead, as it will have more
detail and will also know if Apple did something funny which makes the
above instructions not work.

Todd Whitesel
toddpw @ best.com