Skip to main content
Home Forums OC Q605/LC475 25mhz===>33mhz so easy! — #7 OC Q605/LC475 25mhz===>33mhz so easy! — #7
Post #7 by uniserver
Post
i figured i would just cut and paste this in,

I'm coming across alot of dead links now a days.

:------------------------------------->

Here is a quick HOW-TO on overclocking Quadra 605s and Performa 475s. I've

successfully overclocked nine of these to 40 MHz, and all are stable and

reliable.

Most of the information is already available from:

http://gabezing.sytes.net/LC475-40Mhz-E.html

That site isn't exactly very clear on certain things; so, to simplify,

here is what you need to do:

1) Perform the resistor swap as indicated to bring the system to 33 MHz

(this decouples some other clock, I guess; the system won't be stable at

40 MHz without doing this)

2) Get a 20 MHz oscillator and connect pin 7 (or the equivalent) to pin 7

of the 31.33 MHz oscillator on the rear right corner of the motherboard;

also connect pin 14 to pin 14. These are ground and +5 volts, respectively

(20 MHz oscillators can be bought from, say, Digikey(.com))

3) Remove R93 from the back of the motherboard. Then run a short wire from

pin 8 of the oscillator to the R93 pad that is closer to the middle of the

motherboard.

That's it! I know this is basically what that web page says, but I hope my

language is a little clearer.

Finally, of course, if you want to run NetBSD now, you'll need a real

68040, not an LC040. We're still working on creating a binary snapshot of

a NetBSD system that does all floating point via software.

Then go buy a 64 meg SIMM for $12 USD and you'll have a very happy Quadra

605!

John Klos

Sixgirls Computing Labs

mp.ls