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Power Mac G4 QuickSilver Overclocking Instructions

G4 QuickSilver Overclocking
(Optimize your Processor!)


THIS IS FAIRLY HARD TO DO! I don't recommend trying this unless you are willing and have the funds to replace your processor and have had experience with micro soldering.


I like to think of it more as OPTIMIZING my G4 Processor. To some folks the term overclocking has bad connotations. Optimizing your Macintosh G4 Tower (QuickSilver Motherboard) is an inexpensive get more speed. It does require a high level of skill, good desoldering skills, steady hands and good vision and or magnifying equipment. Almost all G4 QuickSilvers will overclock at least one level. In other words, your 733 will probably run 800 or your 800 may run 867. Most G4 processors were very capable. Your machine should be in good working order. Overclocking will make any existing problems worse. Good well tested and well seated ram, a fresh install of the OS and a clean bill of health from Disk First Aid or the disk utility of your choice is a good way to start out any upgrade project. These notes assume that you know how to open your case and feel comfortable poking around the insides of your computer. If you are a hamfisted klutz it is better to pay someone with the expertise. Understanding that electronic components may be static sensitive and you have taken appropriate precautions are important. I recently had a user call who broke the plastic catch that the heat sink spring attaches to. Let me repeat if you are a bit ham fisted it pays to have someone with experience do this for you. The user bought another system.. I would have used epoxy (super glue won't work!) to repair a break like this but again you need experience using epoxy on delicate materials. If you aren't comfortable doing your own repairs there are always folks like us who are happy to help.

When I was 16 I bought my first car. It as an old Ford 6 cylinder. I was tuning it up putting in new plugs and points and a friend stopped by. He said we need to check your pedal. I didn't know what he was talking about. He told me to hang on to the throttle cable and got in the car and pressed the gas pedal to the floor. The throttle as about a 1/4" from being totally open. He helped me optimize my carburetor. He said that most car makers never give you all the pedal. I never did know why but perhaps they had their reasons. From then on each new or used car I bought got optimized. I want all the pedal.

Computers have processors and that equates to an engine in a car. The manufacturers have to make sure your computer runs under a wide ranges of circumstance and that sometimes they compromise reliability over performance. Now I don't know about you but I don't run my computer in a 100 degree room. If I did I might have problems bumping up the processor speed. Some of the units we sell have had their processors optimized. We note them in the descriptions if this is so. We test them to insure that they are reliable at the higher speeds.

Motorola, and IBM manufacturer the processors. Apple many times set the speed levels very conservatively. We sometimes bump those processors one notch and thoroughly test them and check temperatures at the next higher rating. If they aren't rock solid we don't sell them. Many very possibly would be stable at even higher ratings. We also make sure that your heat sink is in solid contact with the processor and in some cases use a silver heat sink compound to insure your unit is running as cool as possible and many times cooler even at the higher ratings than the stock unit was running. Some of our servers and many of our work stations which run 24/7 for years have done so with optimized processors.

I think you deserve to have all the pedal your computer has to offer without sacrificing reliability.

Remember if you foul up the processor you will have to replace it. If you are not prepared to buy a replacement or upgrade do not start. You possibly could damage your motherboard if you don't make sure the pins are properly aligned on the processor before applying pressure.

NEVER turn on the machine with the heat sink off of the processor. In fact unplug the machine while you have the heat sink off.


If you use thermal grease a small amount is simply a very tiny amount. Keep in mind that when the heat sink is clamped down it is going to spread. A thin film covering the processor is all that is required. Too much and it gets under the gasket and shorts the capacitors. I sometimes apply a thin film on the heat sink gasket almost wiping it back off. This prevents the processor from welding itself to the gasket and probably puts as much heat sink grease as anyone needs. I like an use the silver based compounds.

It is okay to boot your machine for a minute or two with the door open. Keep the time down to a minimum. The processor relies on the large interior fan to cool off the heat sink. For purposes other than a quick test you should always have the case closed up.

You do this at your own risk. I make no claims or warranties about this information and working on the insides of anything electronic may result in you messing the things up. Please note that any modifications you make to your Macintosh are made at your own risk.

G4 QuickSilver Processor Backside
Backside of processor, note PLL position in RED.
G4 QuickSilver Processor PLL Location

Note resistors on R1 and R5 making this an 867 mhz processor. Also NOTE that the resistors are not numerically aligned.

Some of the images and chart are from the website. Since the original was in Japanese and sparse on info, I converted them to English.


Apple Power Macintosh G4 Quicksilver model

First things first: Use Apple System Profiler to determine what your present clock speed is. On the diagram below find out how many traces are required to set your system's speed up to the next level. You will need a trace pen like those used to repair automotive rear window defoggers. I use a pen called the Circuit Writer but these are increasingly hard to find. They don't work very well and clog up almost instantly. I ended up opening the pen by screwing off the tip and using a toothpick to paint the traces.


  • Remove the cooling fan by taking out the two screws from the back of the computer. Unplug the fan from the motherboard. Clean the fan. If you use your wife's makeup brushes don't let her catch you.
  • Use needlenose to remove the heatsink clips popping loose the front of the clips first. Use a small flatbladed screwdriver to pop loose the back of the clips. Be extremely careful not to damage the motherboard beneath the clips. Note orientation. The dimples that contact the heat sink must be replaced in the same position. If you forget simply hold the clamps over the processor. The dimple should be centered over the copper processor center. I bend the spring clamps (very slightly) equally on both sides so that they put a bit more pressure on the heat sink to insure a good contact.
  • Pull the heatsink straight up and away and set aside.
  • Remove the 4 phillips screws holding down the processor.
  • Between the topand bottom screw on the right side of the processor underneath is a plug. I put my finger under this point and grab the left corners of the processor board and pull straight up.
  • Turn the processor over being careful not to bend any of the tiny pins.
  • Carefully desolder the resistor(s). You should view the chart below and make a strategy before beginning. For example on the 733 to make it 800 you simply desolder one resistor. A dental pick is handy for removing the resistors once you have melted the solder. Be careful not to apply to much heat or sling the solder when you remove the resistors.
  • Carefully paint in your traces. I use a toothpick dipped into the solution from the Circuit Writer Pens (Try and search for circuit writer). Use a dental pick or small knife to clean any excess off. Once you have completed your traces and are ready to reinstall simply reverse the procedure. Make certain you are lined up and push straight down to seat the plug. Any misalignment here and pressure will bend the pins and make the processor unusuable and may damage the motherboard.
  • ONE THING I HAVE LEARNED: the trace needs to be fairly thick to give the proper connection. On units that fail to work, I usually simply add another layer of the solution to build up the trace and double check to make sure I have cleaned up the excess so that no contact is made elsewhere.
  • Reinstall the screws, don't overtighten.
  • Add a dab of heatsink grease to the black pad on the bottom of heatsink and wipe most of it off leaving a very thin almost see through layer. Almost better to have too little than too much. If excess works its way under the processor gasket it can cause failure. If part of the black gasket is stuck to the processor, clean it off and apply a bit more grease to the gasket to fill in the voids.
  • Replace the spring clips in the same orientation that you removed them. If you weren't paying attention the dimples are positions about the processor itself.
  • Replace the fan and plug it back in. Return your wifes make up brush (I use a little spit to clean the dirt from the brush). Button up the case and start up your system. Your system relies on the air flow of the closed case for proper cooling. Running your computer with the case open for more than a few minutes can cause overheating.

Your system should make the normal startup chime and reboot. If it doesn't push the PMU switch behind the battery (it looks like a tiny gray doorbell button) and count to 5 slow. Try it again. Still no luck? Take it back apart and check your traces. Make sure you haven't jumpered to any parts unintended and use a small point to clean off any excess material. Make sure your trace goes from solder pad to solder pad. If it still doesn't work, put things back the way they were or order a processor replacment or upgrade.

If it works okay check Apple System Profiler to see if you are running at the desired speed.

I usually load up a few Applications to see if I notice any anomolies. Run disk first aid which uses the processor, and drives fairly heavily. One of my techs (Scott) like to run the Graphing Calculator in demo mode which works extremely well for testing. If you have the old Test Memory 1.0 program run it in repeated mode for a few hours. If you have any freezing or other difficulties then redo the original setup and call it a day.

If you are successful you may wish to try the next level of speed up, but I don't recommend it. Keep in mind rarely will you get a stable machine at going a full 100 mhz increment. I have optimized about 100 processors so far and all but one has went one bump up with no problems even after lengthy testing. The one that failed I accidently drug solder sidewise as I was removing the resistor. Next time I have the iron fired up I probably can get it to work as well. I think the 450 mhz processor and the 500's are the exact same chip but can't prove it. The 450's all run 500 as stable as the original 500's. I think the same is true of the dual processor 450's after having optimized a few dozen of them now. I have only upgraded a few 466 Digital Audio's with no problems. Recently we bumped a few 733 mhz QuickSilver's to 800. They all passed with flying colors. I have also bumped a few 867 mhz to 933 mhz and they have all worked fine so far.


Multipicator CCU

0:Set Jumper
x: NO Jumper

NOTE: that the resistors are not numerically aligned. See the image above for the numbering sequence.


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