OC Q605/LC475 25mhz===>33mhz so easy!

[uniserver]

http://web.archive.org/web/20040803184138/http://gabezing.sytes.net/475clockup33Mhz.html

i followed this old article from applefritter,

and it really is this simple, the oc is worth it, you can really tell!

also to go one extra step , i'v installed the full 040 as well, with thin heat sinks.

This is so easy its crazy not to do it.

(unless you are trying to keep your machine stock)

i made the following image.

 

[Byrd]

Yep it's such an easy mod, and the resistors are quite large to work with (good practice for removing the really tiny resistors you get on later Macs, for overclocking)

 

[Trash80toHP_Mini]

Nice job, great graphic, thanks for the reminder . . . I've been a bit busy . . .

. . . I still haven't done any of mine yet . . . and I've had a 33MHz 68040 w/heatsink in one of them waiting for a clock chip for about eleven years now . . .

. . . I guess I should get around to it. It's not like I don't have spares . . . :I

 

[uniserver]

yeah you should get on it, its one of the easier OC's i've ever done,

The Slot load iMacs were much harder, most of those wouldn't go too much past a 50mhz speed bump anyways.

the G3 Blue and white powermac's were easier, just used a thumb tack, but most of the time you didn't want to go

more then 50 mhz with those ether.

 

[Trash80toHP_Mini]

I was hoping that with the 33MHz Proc, the clock might be pushed closer to 40MHz, but I never really looked into it . . .

. . . I've had more than my share on the plate, lo these many years. :-/

LCGuy's tag line sig comes to mind! )

 

[uniserver]

cpu clock is completely controlled by the main board.

the full 040 i have installed says 25 mhz right on it, probably from a q700, its running just fine @ 33 mhz,

you can do more soldering, and get an oscillator, to make it run at 40/42 mhz.

here is the apple fritter article:

http://www.applefritter.com/node/20510

another Q605@40mhz article:

http://mail-index.netbsd.org/port-mac68k/2002/05/31/0006.html

 

[uniserver]

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

 

[Trash80toHP_Mini]

Thanks, I'll be on that . . . any day now!

Meanwhile I'm beating my brains out on the very sturdy case of the Radius 81/110, just trying to get the Sonnet G3 up and running . . . HA! 8-o

I'm glad I stopped in, maybe if I unplug that dratted PDS Extension Cable! :approve:

My cold sounded bronchial to the sawbones, so I'm off another day to deal with some of the backlog . . . indescribably GeekGreek. [] ]'> [] ]'>

 

[trag]

Most of the information is already available from:

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

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.

Huh!? No need to replace the M88916DW or M88920DW chip? That's cool.

Did you need 80ns VRAM?

 

[uniserver]

i just preformed the 25 to 33mhz OC, (Works Great)

That 40mhz Document, I cut and pasted that in from a netbsd email archive.

http://mail-index.netbsd.org/port-mac68k/2002/05/31/0006.html

 

[Trash80toHP_Mini]

I think I'm geeked out for today . . . it's Greek tragedy mask for now . . . with a corner of the comic mask peeking out from under as well . . .

. . . I'll elaborate in the relevant threads to keep this one clean. Meanwhile, my list of oscillators now includes 20MHz for the MicroQuadra as well as 24MHz, so far, for the VidCard.

Thanks gang! :approve:

 

[uniserver]

mcdermd just preformed this to a LC475, with success! He ended up using Arctic silver 2 part, to secure the heatsink onto the cpu.

 

[mcdermd]

It pains me to use thermal epoxy instead of a heatsink clip but the machine is for uniserver and I know that he isn't ever going to clock it back down to 25mhz and even if he does, the heatsink won't be doing any harm.

 

[uniserver]

I would like to make an interesting point.

I am overclocking a stack of 475/605 boards here for a buddy.

One of the boards was missing a cpu so i threw my 40mhz full 040 cpu from my old 840av.

anyways i thought that it was interesting how after the OC to 33mhz the cpu got quite warm but i could still mostly touch it

with out pain.

normally when you toss a 25mhz full 040 in there, and clock that bad boy to 33mhz... it gets really hot and needs a heatsink.

So i guess what i am saying is if you can get ahold of a Q840av 40mhz cpu, and install it into your q605/475/575 looks like you will not need a heatsink

@ 33mhz.

 

[CC_333]

Well, logically, probably not. Since you are actually underclocking the 40 MHz CPU, it shouldn't run hot at all because it's running at most 7 MHz less than its rated speed.

c

 

[uniserver]

i still have to get around to ocing my q800 to 40/42 mhz so this cpu can finally have a proper home. just been so busy.