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#1 2014-08-30 00:18:42

Registered: 2014-05-29
Posts: 1,064

Ye Olde overclocking document

I was going through some old CD images and found this text document from 1994 on overclocking macs.  I'm not big on the overclocking/accelerator idea, but it was an interesting piece of history anyway:



First some disclaimers from PowerPC News: Modifying your Macintosh in
any of the ways below will certainly void your machine's warrantee. In
addition you will be driving your machine's processor faster than Apple
designed it to go, and therefore the possibility of long-term damage to
the machine does exist. PowerPC News can not recommend that you modify
your Macintosh and we are providing this information on an as-is basis
and cannot be responsible if the result is a non-functional machine, or
indeed a sticky smoking blob in the middle of your desk. The following
file is republished from the ftp site where it is
maintained by Marc Schrier and we are not responsible for its content.

That had to be said. Nervous enough? Good - now read on.

By Marc Schrier <>

Mac Crystal Oscillator Speedup History 2.3                April 1994
There has been a great deal of interest expressed over the net about
these simple and inexpensive Macintosh modifications that yield 20- 40%
speed increases.  Over the last year or so I have been doing a  fair
amount of crystal oscillator swapping/acceleration on Mac's,  and
gathering information from others.  I've made several posts to
comp.sys.mac.hardware with the bulk of this info and as new  machines
come out, and new concerns surface, I will try to add them  to this
history of the modifications, post them on  comp.sys.mac.hardware and
make them available for anonymous ftp  on in
/info-mac/info/hdwr.  Included in this  version is some of the news on
the PowerMac's and Marlin Prowell's  new C650 modification.

A little background:
All computers operate at a certain frequency with which operations  are
performed.  Within a certain class of computers, for example  Mac's with
a 68030 processor, the higher the frequency, the higher  frequency of
operations processed, and the faster the computer  provided there is no
other speed effecting hardware like a cache or  slow data path.  The
designer of the computer, Apple in this case, will use components that
are rated at the same frequency or faster  than the final computer will
be.  The 68030's are made by Motorola.   All 68030's are generally alike
in what they do, but they are not  alike in how fast they can do it.
Motorola sells several 68030  processors rated at 16, 20, 25, 33, 40 and
50MHz for Mac's,  accelerators and such.  A large frequency difference
will require a  different mask during production of the processor, but
small changes  may not.  Motorola only needs to guarantee that the chip
they mark  as 20MHz will function properly at 20MHz under a variety of
conditions.  Some chip vendors will test parts at different  frequencies
and sort the chips accordingly while others may just  label the them at
will and sell the chips at the different price as  long as they are
within spec.  So it is possible that the 20 and 25's  actually come from
the same batch, are separated on demand, and  tested to make sure they
will withstand that frequency.  Because of  this, it is possible that a
20MHz processor will function fine at a  higher frequency, say 25MHz.
Running it faster will however  generate more heat. 

Many of the components in the computer need to be synchronized, so  a
frequency is generated by a crystal oscillator to synchronize them. 
Other parts like NuBus cards and video do not have to be the same
frequency, so they may have separate crystal oscillators.  A typical
computer may have several crystal oscillators to clock different  groups
of components on the motherboard.  Provided the components  that are
clocked by a particular crystal oscillator are capable of a  speed
increase, that crystal oscillator may be replaced with one of a  higher
frequency.  How much a specific Mac can be sped up by this  method
depends on how the motherboard was designed, the  components used, and
what things the crystal oscillator that  controls the processor also
controls.  With some of the newer Mac's,  there are a few MHz
differences in the top speeds reported for the  same model, so part of
this is luck of the draw.

This crystal oscillator swapping has been done for years, and some
early computers even had jumpers that made it really easy to  disable
one oscillator and enable another higher frequency one.  The  first
Mac's to be modified were the IIsi's.  A stock IIsi's runs at  20MHz,
and IIci's at 25MHz, and since the architecture of these  machines was
so similar it seemed reasonable to run a IIsi at IIci  speeds.  Another
important factor was that earlier Mac's had just  one crystal oscillator
that controlled everything, and if you replaced  it you would mess
things up.  The IIsi was different as some noted  through its frequency
deviation from its 8 and 16MHz precursors  where the main frequency was
halved and quartered to run the CPU,  serial ports, video...  The IIsi
was different, it had 4 crystal  oscillators, only one of which
controlled the processor speed.
The Crystal Oscillator:
The type of crystal oscillator in the early Mac's is a full size, 14 pin
package, TTL type crystal oscillator.  It is a rectangular metal can,
with approximate dimensions of 2.0 x 1.3cm and typically about 0.3-
0.6cm high.  All crystal oscillators have 4 pins.  Some are numbered
1,2,3,4 and others 1,7,8,14.  Pin 1 is always the pin next to the
pointed edge (the others are rounded), with the dot, or next to the
indentation on the newer CMOS, or surface mount crystal oscillators. 
With the pins facing down, put the dot, or indentation to your left,
and the pin on the left, closest to you is pin 1.  Going counter
clockwise, pin 2 (or 7, depending on what numbering scheme) is to  the
right, Pin 3(8) right side and further away, and 4(14) left side,  and
further away.  Pin 1 on all the newer Mac's with surface mount  crystal
oscillators, and some of the older ones is an output  enable/disable pin
(OE).  On some of the crystal oscillators you  purchase Pin 1 will be
OE, yet on many it will not be used (no  contact (NC)).  It is not
important which you get as you will not be  using the output enable
feature.  Pin 2(7) is a ground.  Pin 3(8) is the  output.  Pin 4(14) is
the supply voltage, +5 VDC.  I've checked a few  of the older type
Mac's, and the oscillator on Mac Plus's is not OE,  while the ones on
the IIsi's and Quadra 700's are OE.  I'm not sure  why Apple uses these
type of oscillators instead of the ones where  pin 1 is not used.  I
guess it is possible that something on the circuit  board can ground pin
1 and stop or restart the computer.  If anyone  knows, please let me
know.  Printed on the crystal oscillator will be  its manufacturer, part
numbers, and frequency.  On these early Mac's,  the processor runs at
half the speed of the oscillator, so a 20MHz  Mac IIsi has a 40MHz
crystal oscillator. 

There are several different modification techniques.  They will all
give you the same final max speed.  Some are just easier or more
elegant than others.  As with all these modifications, even though
there may be no visible sign that you modified your Mac, you have
voided the warranty on the Mac.  As Apple states:
"This warranty does not apply if the product has been damaged by
accident, abuse, misuse, or misapplication; if the product has been
modified without the written permission of Apple; or if any Apple
serial number has been removed or defaced."

This is what I seem to be finding.  These numbers vary from Mac to  Mac,
so these are just averages.  Some machines will go faster than  this.
These are the oscillators that Output Enablers ships in their  kits.


Machine   Mod-1   Mod-2   Mod-3   Oscillator/speed   Final
IIsi      yes     yes     no      40/20              55/27.5MHz
C610      yes     no      yes     10/20              14-14.31818/28.6MHz
C650      yes     no      yes     12.5/25            14.31818-14.75/29.5MHz
C650-mod  yes     no      yes     12.5/25            20/40MHz
C660av    yes     no      yes     12.5/25            16-17.496/35MHz
Q610      yes     no      yes     12.5/25            15-15.288/30.6MHz
Q650      yes     no      yes     16.6667/33.3       21-22/44MHz
Q660av    yes     no      yes     12.5/25            16-17.496/35MHz
Q700      yes     yes     no      50/25              70/35MHz
Q800      yes     no      yes     16.6667/33.3       20-21/42MHz
Q840av    yes     no      yes     20/40              23.247-24/48MHz
Q900      yes     yes     no      50/25              70/35MHz
Q950      yes     yes     no      66/33              ?75-80/?40MHz
PM6100    yes     no      yes     30/60              40/80MHz
PM7100    yes     no      yes     33/66              ?45/?90MHz
PM8100    yes     no      yes     40/80              ?50/?100MHz


The basic idea of Modification #1 is removing the onboard oscillator,
and replacing it with a faster one.  This is the mod most people use  on
the IIsi, Q700, Q900, & Q950.

The basic procedure used is that you have to unsolder the TTL  crystal
oscillator from the motherboard on the Mac, and put in a new  one.
Instead of putting one straight onto the board, it is nice to use  a
socket so you can test your individual Mac, and see what the cutoff
frequency is, and you can always put the original oscillator back in
the socket.

First find the crystal oscillator by referring to the previous table
and description of physical characteristics.  Be careful when you
remove the oscillator.  Most people just use a normal soldering iron,
and are fine; a grounded (three prong soldering iron) would be a bit
safer.  They just use copper wick to soak up the solder from all four
pins, and pop out the proper oscillator.  Because the boards are
multilayer, be careful not to damage anything; be gentle.  There was
recently one report of a guy who damaged his IIsi board doing this. 
But that was the only incident I had ever heard of, and lots and lots
of people have done this.  I use a "desoldering iron".  They melt the
solder, and have a pump to suck out the solder while you swirl the  pin
from the oscillator around to get all the solder out.  After you  have
done all 4, if you have done a good job, the oscillator just pops  out.
If you have access to one of these desoldering irons, I highly  suggest
you use it as it does a cleaner job, and there is less risk of  burning
(discoloring) the board.  Next, take a 14 pin IC socket,  remove all the
pins but 1,7,8, and 14, and solder it into the board  (see Modification
#3 for a Digi-key part number).  Make sure you put  it in so pin 1 will
go into pin 1, 2-2, 3-3, 4-4.  And the notch in the  socket should face
the same way the dot on the old oscillator was  facing.  Now just put in
a faster oscillator.

I have done this to a few IIsi, and the highest frequency we could get
to work without problems was 27.5MHz.  Thus a speed increase from  20 to
27.5MHz.  The actual crystal is 55MHz (double the frequency).   TTL
55MHz crystal oscillators do exist, but they are rare.  The thing  most
people seem to do is get a CMOS oscillator, and they work just  fine.
Digi-Key sells a 55MHz CMOS crystal oscillator in a 14 pin  package,
part# SE1509.  At 58.9 and above, there are problems with  the floppy
drive; you cannot boot the Mac from a floppy, but other  than that it is
fine until just over 30MHz.  I recently had a IIsi at  28.3MHz and it
was fine.  Be warned that some cards may not work  after this
modification.  Most will work at 25MHz, but will not at  27.5MHz, so
just stick with 25MHz if that is the case.
The IIsi does not come with a heatsink, so to reduce the heat in the
processor, get a small heat sink to attach to the 68030 to cool it
down; any heat sink will do; the more surface area the faster heat  will
be dissipated.  Be careful when you put on the heat sink.   Typically
you'll use some heat transfer grease, but the heat sink can  slide off
if the Mac is moved, and the heat sink might short  something out.  The
best thing seems to be to get a heat sink with a  hole in the middle, or
drill one yourself, use the heat transfer  grease, but also put a small
drop of super glue through the hole in  the heat sink onto the chip or
put a drop on the side, and this should  hold it in place.  Fry's sells
nice heat sink/fan combo's.  They run $10  and up, and I think they are
more than you need, but it should keep  the processor cooler.  I believe
they come with a Y cable to tap into  your hard drive power cable to
power the fan.  A more complete FAQ  on this modification for a IIsi is
available via anonymous ftp from in
info-mac/info/hdwr (iisi-25mhz-upgrade- faq.txt).

For the Quadra 700 and 900, you can get 70MHz TTL crystals from  Fry's.
The 70MHz may not work, and you may have to back down to  66.6666MHz,
the next most common frequency, Digi-Key part#  CTX137.  The Q700, Q900,
and Q950 come with a heatsink installed.   A more complete file on this
modification for a Quadra 700 is also  available via anonymous ftp from in info- mac/info/hdwr

It has been reported for, but I have not yet done a Q950, but the
general idea is the same.  If anyone has any more info on doing a  Q950,
please e-mail me and I'll add it.


The basic idea of Modification #2 is to disable the onboard  oscillator
with a jumper and feed in a new signal on the back of the  board.  There
are very few who have performed this mod, but I feel it  is more elegant
and safer since you don't have to remove the onboard  oscillator.  This
newer, and less evasive method has been performed  on IIsi's & Q700's by
myself, and should work fine on the Q900 &  Q950.

The most difficult and risky part of "Mod-1" above is the removal of
the oscillator, and this is an alternative procedure that gets around
that since the crystal oscillators Apple uses have pin 1 as OE.  On a
crystal oscillator with pin 1 as OE, if you ground pin 1, you disable
the output from pin 3(8), and you can feed a new signal into pin 3(8)
without removing the original crystal oscillator. Several months ago I
performed this modification on a Quadra 700 by  tacking (soldering) a
jumper on the back of the motherboard between  pins 1 and 2(7) of the
50MHz oscillator, and ran wires about 8 inches  long each from pins
2(7), 3(8), and 4(14) to a 14 pin socket attached  to the inside of the
Q700 with pins in positions 7, 8, and 14.  Into  this we placed a 70MHz
crystal oscillator and the Mac ran fine at  35MHz and is still doing
fine.  This modification is nice in that it is  a bit less risky as far
as damage to the motherboard, but you have to  be careful to use thin
wires in order to make clean solder joints.   With this modification you
could remove the wires at a later date to  return to the original
configuration more cleanly.  I cannot say for  sure if this will work on
a Q900 or Q950 until I put one of those  crystals on a scope, or
actually try the modification, but am pretty  sure it will.  If anyone
has removed a crystal from a Q900 or Q950  and still has it, I'd be glad
to check it out and send it back to you.


The basic idea of modification #3 is building a clip that disables the
onboard oscillator, and feeds in a new, faster signal.  The beauty of
this modification over the others is that you do not have to do any
soldering on the motherboard itself, just on the part you clip onto  the
surface mount crystal oscillator in your Mac.  This is the  modification
most people use on the C610, C650, C660av, Q610,  Q650, Q660av, Q800,
Q840av, PM6100, PM7100, PM8100.
The really neat thing about this came into play in February 1992  when
Apple released the Centris 610, 650, and Quadra 800.  In these  machines
and since, Apple has been using surface mount crystal  oscillators.  Now
that Apple was using surface mount crystal  oscillators, there was
plenty of accessible area on the metal tabs of  the oscillator.  In June
'93 Guy Kuo reported the first crystal swap  of sorts on a Centris 610
to the net.  He soldered pins 3, 5, 10, and  12 of a 14 pin socket
directly onto the surface mount crystal  oscillator.  Because the pins
on a TTL type crystal oscillator are at  positions 1, 7, 8, and 14, he
made jumpers between pins 5-7, 8-10,  and 12-14.  He disabled the
on-board surface mount crystal  oscillator with a jumper between 3-5.
Then put the new crystal in  the socket.  This file is also available on
SUMEX in info- mac/info/hdwr (centris-610-clock-mod-11).
I was a little hesitant about soldering onto my new Quadra 800, so
wrote to him a few days later about using a surface mount test clip,
and asked his thoughts.  He suspected I could not find a reasonable
test clip, but otherwise believed it would work.  A few days later  the
3M surface mount test clip arrived, and the test clip worked  perfectly.
I was running my Quadra 800 at 40MHz, with no problems,  and best of all
the modification was all contained in a simple little  clip that could
be removed without trace at will.  And thus the  removable test clip
approach was born.  My Q800 even worked at  48MHz as long as I did not
access the serial ports.  A few days later  I got several crystals, and
found the highest frequency on my Quadra  800 to be 42.0MHz.  Since then
I've tried it at 42.106MHz, and the  serial ports did not work, so the
cutoff for my Q800 was at 42.0MHz.   If you never use your serial ports,
48MHz worked fine for me, while  at 50MHz my Mac was not happy and would
not boot.   
So if you are still interested, you will need a surface mount test
clip; 3M and Pomona make them, and I prefer the 3M ones.  Make sure  you
get a surface mount test clip.  The I.C. test clips also work, but I
prefer the surface mount SOIC (small outline integrated circuit)  ones.
A 10, 12, 14, 16, or 18 pin clip will be fine.  I'd say go with a  14 or
16 narrow or wide.

14 pin, part# 923650-14-ND  $6.58
16 pin, part# 923650-16-ND  $6.96

These are the part numbers for the ones with alloy leads; I used to
recommend the gold coated ones, but the resistance/corrosion effect  is

You will also need a 14 pin IC socket, there are plenty of types.  The
machined pin ones are nice because you can pop out the pins that are
not needed to get them out of the way since you only need three pins  in
the socket.

14 pin IC socket w/tin pins, part# ED3114  $0.57
You will also need an oscillator (more on this later), a little wire,
soldering iron, solder, and possibly heat sink depending on the
machine.  For a C610, C660av, Q610, and Q660av you should add a  heat
sink, HS160-ND is the 0.600 inch one, and is plenty ($3.98).
The others already have heat sinks, and do not get too hot.  I had an
extra fan with my Q800, but removed it, and it has been fine.  The  heat
sinks come with the clips needed to attach them to the chip.   These are
a bit of a pain, you just have to work at it for a while.   There may be
several ways to do it, but I just slide the clips on from  the side.
Sometimes they fall off half way there, but eventually it  works.  Some
people have been using the heat sink/fan combo's.  I  have not, but they
seem to work fine as well.  The new Q610 and  Q660av computers are based
on a new mask of the 68040 that comes  at 25MHz without a heatsink
(There is an "H" after the '040 and  before the "RC").  This is the same
mask as the C660av and Q840av  uses.  If you do the modification on them
it would be best to add a  heat sink.

How to put it all together:

Stand the clip so it's jaws are facing down, and the rows of pins go
>From left to right, and call the closer row A and the further row B. 
Number the pins from left to right 1 through 7 (for the 14 pin clip). 
Next place the IC socket with the pins down, and the notch to the  left,
and number the pins as 1, 2, 3, 4, 5, 6, 7 in the row closest to  you,
going left to right.  The other row is numbered 8, 9, 10, 11, 12,  13,
14 as you go right to left (back towards the notch). Now starting with
the test clip, leave pins in positions A2, A6, B2,  and B6.  Next solder
a little jumper wire between pins A2 and A6.   Now get the 14 pin IC
socket, and remove all the pins but 7, 8, and  14.  Solder a jumper wire
from pin 7 on the IC socket to the  jumpered pins on the clip, either A2
or A6.  Also solder a jumper  wire from pin 8 to pin B6, and pin 14 to
pin B2. If you get the narrow clip, you may want to replace the spring
with  one with less tension; they are like $0.30 at hardware stores, and
I  cut them into two springs.  This way you don't have to push so hard,
and it is easier to position on the motherboard.  Now put the crystal
in the socket with pin 1 in 1, 2 in 2, 3 in 3 and 4 in 4.
There are several surface mount oscillators used on the  motherboards.
The proper surface mount crystal oscillator on the  mother board will
have a frequency on it half that of your computer  and can be determined
from the above list.

That is it, now you just clamp it onto the surface mount crystal
oscillator with the notch on the socket facing the same way as the
surface mount crystal oscillator.  And watch to make sure the little
pins clamp onto the surface mount chip.  You may want to use a
flashlight for this.  These clips hang on very, very well, I've never
had mine move in the last 9 months, nor any of the other ones I've

Centris 610 Ethernet Problems:

Those Centris 610's that have ethernet capability share the 10MHz
oscillator with the CPU.  If you replace that oscillator with a
different one, your ethernet will no longer work.  In January, Eckart
Hasselbrink ( posted a fairly simple
hardware modification to fix this to comp.sys.mac.hardware.  So if  you
plan to use you ethernet on your Centris 650 and speed it up, you  will
need to perform Eckart's modification first.


I have only done PM6100's, and it works fine at 80MHz.  At 86MHz it
overheats quite rapidly.  With a cool hairdryer cooling the heatsink  on
the 601, it worked fine, but was a bit noisy :-).  See the table to  see
which oscillator you will need to clip onto.  This mod should  work just
fine on the 7100 and 8100 computers as well.  On the  8100 the power
supply may be in the way of the clip.  If anyone in  the Bay Area has a
PM7100 or PM8100 and wants to try it, drop me a  line and we can give it
a spin.  Or if anyone tries it, please let me  know how it goes so I can
add it to this file and pass it on to others  who ask.  The guesses on
the chart about what oscillator to use for  the PM7100 and PM8100 are
just that, guesses.

On most of these newer machines, the problem is with the serial  ports,
but the speed of the memory is also important, so if you plan  to boost
your Mac very far, you may need faster SIMM's.
To test out the modification, the best thing to do is just use it a
while.  You can run Speedometer 3.23 (available at SUMEX in info-
mac/cfg) to see the changes.  I use Snooper with the serial port
loopback plugs to check the serial ports to find their limits; Snooper
also tells you what frequency you are running at in round numbers. 
Snooper was made by Maxa, and I am told Snooper is currently owned  by
Central Point Software.  The current version of MacCheck is 1.0.5
(available on, and it now properly reports the
computer frequency.

If your Mac does not give the standard chime at startup it means  your
clip is only half on.  It is disabling the surface mount  oscillator,
but not replacing it.  Just remove the clip, reposition, and  try again.

Special C650 Mod:

Using the above clips, the max frequency for a Centris 650 is about
30MHz before you encounter serial port problems.  Marlin Prowell
( following up on a hunch by James McPhail
( looked into the differences between the C650  and
Q800 motherboards in hopes that a simple modification might  enable the
serial ports to function properly at 33MHz (Q800 normal  frequency) or
higher.  On the bottom of the motherboard, under the  IOSB chip, Marlin
found two differences.  R151 is installed on the  C650's, and is missing
on the Q800's.  R152 is missing on the C650's,  and is installed on the
Q800.  R151 is a 300 ohms resistor and R152  is a 1.2k ohm resistor.
Looking at the bottom of the board, with the  back away from you, R151
is 3 3/4" from the right, and 3" down.  The  tabs for R152 are 4" from
the right, and 3" down.  R151 is black, and  says 301 on it.
Marlin felt that R151 was glued to the board, and just using solder
braid he was unable to remove the resistor for fear that prying it off
may damage the traces that run under it.  Heating the resistor with a
soldering iron Marlin was eventually able to soften the glue and  remove
the resistor.  Or you can use James McPhail's two soldering  iron
Western technique with a soldering iron in each hand to heat  each side
simultaneously and flip the resistor off the board.  Now  just add the
R152.  Marlin suggests holding the surface mount  resistor in place with
a small screwdriver while soldering it to the  exposed pads on the
Marlin has since used both the serial and modem ports error free  while
running his C650 at 40MHz, and MacCheck reports no problems.   He has
also checked to make sure the ethernet works, and it does.   Since
Marlin's initial modification, it has been confirmed by at least  three
people.  On some of these Mac's the CPU overheats after a  while, so
Marlin suggests you add a fan to dissipate the heat faster  >From the
heatsink.  You can also just run a bit slower, say 38MHz.   You can
purchase these 1.2k resistors from Digi-Key, but the  minimum order is
200 of them.  If you e-mail your address to Output  Enablers at, they will send you a free resistor left  over from
Marlin's extra 199.
****This modification makes your Mac think it has become a Quadra  650,
and the Quadra 650 did not exist when most of you purchased  your
Centris 650.  The System Enabler 040 that came with your  Centris 650,
version 1.0, will not work after this modification, and  your Mac will
not start up unless you have already updated the  System Enabler 040 to
version 1.1, the current version.  The System  Enabler 040 version 1.1
is available from your local Apple Dealer, or  you can ftp it from  Marlin suggests you also  put the new enabler on
all your recovery utility disks as well so you  will be prepared next
time something goes wrong.****

Recently a few companies have been started that replace the crystal
oscillator in powerbooks to speed them up, and add a 68882.  I have
some ideas on how to do this, and the precautions to make.  Has  anyone
done it themselves?  I have some info from Virgil Mehalek
( who noted the differences between the 140 and  170.
I'm not going to add that info until it has been attempted, but  if
anyone is interested in a copy of that info I can forward it to you. 
One important addition thanks to Virgil, worth noting now is that
Active Electronics (800) 228-4836 sells the 33MHz MC68882-FN33A  for
$76.95 plus S&H.

Address' for some other parts suppliers:

Fry's Electronics
340 Portage Ave
Palo Alto, CA
(415) 496-6000

(800) 344-4539

Output Enablers
1678 Shattuck Ave.  Suite # 247
Berkeley, CA 94709

There are currently two companies that sell already made clip-on  kits
for the Mac's with surface mount crystal oscillators.
KS Labs
6326 E. Livingston Ave, Suite 131
Reynoldsburg, OH 43068

Output Enablers
1678 Shattuck Ave.  Suite # 247
Berkeley, CA 94709

If you have gotten any of these new machines to work, please let me
know.  Or if you have any questions or comments that should be  added to
this, feel free to e-mail me as well.

                                           Marc Schrier                 


#2 2014-08-30 17:23:08

From: Electron Alley
Registered: 2014-05-26
Posts: 1,118

Re: Ye Olde overclocking document

I have a Q800 with a NewerTech clip-on clockchipper. It came with a heatsink and active cooler for the '040, and I chipped it to 40MHz. It is damn fast in A/UX, but no longer works with its 601 card. No big loss, since it would be a sucky Power Mac by modern standards anyway (allegedly 38MHz works but I want my 2 dollarsMHz, man!).

Machine room (updated for 2019!):


#3 2014-08-31 03:01:40

From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,470

Re: Ye Olde overclocking document

It's nice to see that "page" again, thanks. I got one of Output Enablers clip-ons and haven't tried it out in what's probably over four years that I've had it. Gotta do the IIsi Twins though. big_smile


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ThinkClassic specialises in the use, maintenance, repair, restoration and modification of vintage computers and peripherals.