>  > I have the chance to put a 68040 into my 345... the problem is that i've
>  > herad only about 25 or 33MHz 68040 working in HP's, but there seems to me
>  > a 40MHz 68040. So, is it possible to ust this chip at full speed ( using
>  > an 80MHz quartz instead of 50 or 66 ) ? Will the hardware survive this ?
>  > Will it work ? Is it dangerous to try ?
> 
> I should let Dave Carrel or Herb Peyerl answer this... I think I remember
> Dave mentioning to me that he tried to overclock his 68040 and it wasn't
> pleased... Dave?

I run my 380 clocked at 33MHz.  That's what my 040 is rated at and I never
tried clocking it above that.  Fundamentally it could work, but I can think
of two gotchas.  If your 040 isn't rated to 40MHz, you don't want to burn
it up.  They're built strong, so you can usually over clock them, but don't
go too crazy.  When overclocking I'd be sure to add a good heat sink with
plenty of heat sink goop.  Also there's a limit to how fast your memory
will go.  There is a jumper near the 040 socket marked 25 and 33.  When set
to 33, I believe that it adds in a wait state.  It turns out that I didn't
need this to run mine at 33 (and, of course, it's faster without the wait
state) but you might need it at 40MHz.

Good luck.  Let me know how you do.  If the 40MHz doesn't cost too much
more that the 33, give it a try.  You can always clock it down, and the
oscillators are only about $5.

Dave