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Blue & White G3 Overclocking (Optimize your Processor!)

Upgrade your Mac for just a few dollars. I like to think of it more as OPTIMIZING my G3Processor. To some folks the term overclocking has bad connotations. Optimizing your Blue & White Macintosh G3 Tower (these settings also work on the early G4 Yikes Systems with the G4) is a quick, inexpensive and reasonably safe way to get more speed. Almost all Blue & White G3's will overclock at least one level. In other words, your 300 will probably run 350 or your 400 will run 450. Most G3 processors were very capable and perhaps even factory rated at higher levels than they were marked. 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.
drive hard jumper, drive jumpers, shunts, jumpers for sale online!Order Jumpers Now!

The first things I do before overclocking a unit it to make sure the processor heat sink if in good contact with the processor. I actually bend the clamp (slightly) so that it puts a bit more downward pressure on the heat sink to insure good contact. REMEMBER the dimple in the clamp should be directly over the processor! I have seen machines with these clamps put on backwards and I am surprised the machine didn't overheat and shutdown. I don't recommend that you use thermal compounds since Apple uses a special contact pad on the heat sink (I do sometimes use a very thin amount of Silver Heatsink Compound). I know that some folks do used the compounds but I have seen no major benefit and have cleaned up a few messes of those who tried and used too much. NEVER turn on the machine with the heat sink off of the processor.


I recently had one of the new Powerlogix G3/800 mhz Processors returned. I couldn't and Powerlogix couldn't figure out why the customer's Beige G3 wouldn't work. When I got the processor back and checked it I realized the problem. The customer had put what he considered a small amount of thermal grease on the processor as the instructions said. It was way too much. It actually worked under the gasket and contacted all of the small capacitors that surround the processor (shorting them out). No permanent damage was done but it took me 20-30 minutes to remove the gasket and all the thermal grease.

PowerLogix is now NOT recommending thermal grease be installed on their new 800 and 900 ZIF processors. Thankfully the have added some type of aluminum looking cover that acts as the contact point for the heat sink!

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. We have the high quality silver thermal grease in stock. Order now!

Some folks put fans on their units and in a Blue & White Tower you have room to spare. A ZIF Socket is the same size as a PC SocketA/370 although the retaining clips rarely fit properly. Using your stock clip with a PC style fan may work in some applications. You will need a fairly low profile unit since a tall fan will interfere with closing the case.

Overclock your Blue & White G3 Power Mac!
jumper block, also the same on the Yikes G4
Close-up of Jumper Block

The jumpers are "sealed" under a label and if this label is removed no Apple Authorized Service provider will repair that Blue & White G3 even if the problem or issue is non- motherboard related. Of course your machine is most likely long since out of warranty. I have been building the world's largest ball of these tape seals for some time now.

I will tell you though that 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.

First things first: Use Apple System Profiler to determine what your present clock speed is. On the diagram below find out how many "jumpers" are required to set your system's speed up to the next level. You need to have at least 5 jumpers for most upgrades and as many as 7. These jumpers are also used to reset the configuration of SCSI drives. You can buy them affordably from us, click to order now. We call these the small size jumpers. The ones used on IDE devices are too large (don't try to make them fit).

Remove the tape seal above the stock jumper block.

Carefully and evenly pull up the jumper block and remove it. I use forceps for this, but a careful hand and needlenose pliers or a small hand will work. Set the block aside since you may need put it back on should your system refuse to boot. You may want to mark how it is oriented. There is a dimple on the top of the block that goes toward the back of the machine.

Next place the jumpers on each of the pins in the configuration you need to acheive the next higher clock speed. See the table below.

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 recheck to make sure you have the jumpers configured properly. 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 repair which uses the processor, and drives fairly heavily. If you have any freezing or other difficulties then reinstall the original block and call it a day.

If you are successful you may wish to try the next level of speed up. Keep in mind though that out of the hundreds of processors I have optimized in Blue & White machines I have never acheived more than one level up.


Note that P1 is farthest from you as you face the machine (backwards from beige).

P1 - P11

S:Set Jumper
x: NO Jumper

 Need help with your hardware? Read Bob's Mac Tech Tips


Here is my pages on optimizing (clocking up) complete with chart.
Sawtooth and Gigabyte Ethernet Single and Duals
Digital Audio Single Processor
QuickSilver Single Processor

Beige Clockup | | | |

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