Bryan Vyhmeister wrote:
> Since I can't seem to find a reasonably priced 68060-based system out 
> there, I am looking at the CPU upgrade possibilities for 68k Macs. I 
> have been reading FAQs all over the place about upgrading Mac CPUs. I 
> have read that you can easily swap a 68LC040 out and put a 68040 in its 
> place. I have not found a clear answer on one thing though. Can I put a 
> faster 68040 chip in place of a slower 68LC040 chip? I just purchased an 
> LC 575 motherboard for my Color Classic (which now has a Color Classic 
> II board in it) and I want to replace its processor with a full 68040. 
> It now has a 33 MHz 68LC040 and I want to put in a 40 MHz 68040. Would 
> that work? I am thinking it will not but I am hoping it will. If that 
> would work than I assume I could upgrade my Quadra 650s to 40 MHz 68040 
> chips as well.

That's exactly what I did.  I cobbled one working Q840 out of two, and 
used the spare processor for my Mystic.  Works great.  It still only 
_runs_ at 33MHz (that's dictated by the oscillator, not the chip) but 
there's no real voodoo involved.

The real trick is using a slower-rated chip at faster speeds - 
overclocking.  It doesn't always work.  The chip has been proven at its 
rated speed.  It might actually be capable of higher, but you never know.

Tim

-- 
Tim & Alethea
christtrek.org