On Sep 6, 2006, at 2:03 PM, John Klos wrote:

>> Since I can't seem to find a reasonably priced 68060-based system  
>> out there,
>
> You do know that m68060 upgrades don't exist for Macs (I'm assuming  
> you do...)

Yes, I am aware of that. I was looking at Amiga machines and also  
mvme68k machines (which I would love to use but I don't know enough  
about them to know what to get).

>> 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.
>
> m68040 processors are often overclockable to 40 MHz. I've OC'd  
> many, and I've never seen one that didn't work fine at 40 MHz.
>
> You can swap out an LC m68040 for a full '040 in any system  
> (although it'd be very hard to do that with a surface mount '040 in  
> a PowerBook). The ROMs will be fine with the full '040.
>
> As far as speed is concerned, yes, you can put in a faster chip,  
> but the speed rating isn't really a big concern. It won't run any  
> faster unless you make changes to the motherboard.

I understand.

> The 575s can be safely taken to 33 MHz:
> http://homepage.mac.com/schrier/lc575.html
>
> Quadra 650s and Quadra 800s can be taken to 40 MHz very easily by  
> using 20 MHz oscillators (less than $5 USD from many places  
> online). Quadra 605s / LC475s can be taken to 33 MHz, like the  
> LC575, by just moving surface mount resistors. They can also be  
> taken to 40 MHz by using 20 MHz oscillators, but that's a little  
> more work.

Thank you for the info.

Bryan