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Quadra / Centris 610 Mumbo Jumbo :)


Well-known member
To keep the 68040 in my head from overheating :)


Apple 820-0377-A

Different variants of this motherboard---

20mhz LC /wo Ethernet

20mhz LC /w Ethernet

20mhz Full /wo Ethernet

20mhz Full /w Ethernet

Quadra Variants?

25mhz LC /wo Ethernet

25mhz LC /w Ethernet

25mhz Full /wo Ethernet

25mhz Full /w Ethernet

Picture of a Centris With out Ethernet



Picture of a Quadra 610 with Ethernet


Picture of what ever it is that i have…. Just got from ebay today…

The CPU is a FULL 040 25mhz, its got ethernet chip… but the pads that need a 20mhz crystal are not populated.


Screen shot 2013-02-12 at 2.31.29 PM.jpg

The reason i am confused is after reading this---

http://www.applefool.com/clockchipping/c610.html by the way THANK YOU mcdermd for hosting this!

So looks like i have to give the ethernet its own clock. so i can replace the 10mhz CPU Crystal with a 15mhz one :)

Last edited by a moderator:


Well-known member
My goal is to get mine to run at 25 or 30 mhz, and to use it in my Preforma 6100 case, I think it should work.



Well-known member
The board you have should be a Centris, maybe someone decided to put a FPU into it and this was the only CPU in reach?

Have you tested the board to see if it runs on 20 MHz?

BTW, i also have a C610, including the rare and in germany nearly unobtainable NuBus adapter. 8-o

I don't like the C610 that much. Problem is, people think the knob on the front is to eject the floppy. :lol:



Well-known member
Gotta love the the Power Button / Floppy Eject on the front, I wonder how many people said, what Gives? This is one DEFECTIVE Floppy eject button.

Man, Apple is really going down the hill :)

Yeah the C610, Q610, Preforma/PM6100 case I'm truly not a fan of this case. nope, do not like it.

I'm looking around for a 16.5 mhz oscillator!!!

Then I will take this (25mhz full 040) bad boy from 20mhz to 33mhz, maybe even higher but i'm not going to get greedy!

I have already put the SONIC, Ethernet IC on its own 20mhz oscillator, separating it from the cpu's oscillator.

The Quadra 610 version already has the Sonic on its own oscillator.

The Centris version must have tried to save a little money by sharing the oscillator signal from the cpu oscillator.

Even today they are between 3 and 4 bucks on mouser…. :( +shipping