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Mac Mini Monster (Phase 1): Swapping a Core Solo CPU

by Ted Silveira

Introduction What's Required Overview of CPU swap Benchmark Tests Heat Conclusions

Phase 2...

Introduction

The Mac Mini Core Solo was one of the first Intel Macs, and the only onethat has shipped with an unusual "single core" CPU. This Mini, along withits Core Duo big brother, generated a lot of interest when it first came out,and we bought one to use for testing as soon as they became available.Times have changed, though, and quickly. While the Core Solo Miniprovided a nice speed boost over the G4 Mini, it looks a bit forlorn now thatall Macs have at least a Core Duo and the newest ones sport the even fasterCore 2 Duo. Rather than relegate the Mini to some respectable butunglamorous background task, we decided to try something different: abrain transplant.In short, we decided to put a new Core 2 Duo chip into the formerly CoreSolo Mini to see what would happen. We knew ahead of time that the swapwas possible: A few adventurous souls had already reported successful

swaps on the web. And we also knew that the technical skill requiredwouldn't be too great: The Core Solo, Core Duo, and Core 2 Duo processorsare pin for pin compatible, and unlike many previous Macs, which havetheir processors soldered directly to the motherboard, the Mini's processor issocketed (as are those in the Intel iMac and the Mac Pro).The questions we wanted to answer were

Just how difficult is the CPU swap going to be?Will the performance gain be worth the time and money required?Will the new processor cause the Mini to run too hot and interferewith its normally quiet operation?

What's required

An Intel-based Mac Mini: The transplant process is the same for boththe Core Solo and Core Duo Minis, but of course the benefit will bethe greatest for the Core Solo.A Core 2 Duo processor: We used the 1.83 GHz Core 2 Duo T5600(Merom) chip with the 667 MHz front side bus speed (which matchesthe Mini's FSB speed). The cost at the time of purchase was $250.Intel makes faster versions of this chip (2.0, 2.16, and 2.33 GHz), butthose were universally out of stock (and considerably moreexpensive) at the time.Thermal paste to ensure good heat transfer between the CPU and itsheatsink. (We used Arctic Silver.)Some basic tools: Phillips and Torx screwdrivers, a flat blade (like aputty knife) for opening the Mini case, an anti-static wrist strap.A safe workspace: You need good lighting and a flat, static-free worksurface with plenty of room. Pick a spot where you can safely leavethe disassembled computer and its parts out if you stop due to nervesor interruptions. The kitchen table is probably not a good choice.Neither is any room accessible to free-range pets. (That hamster willpouch the screws while you're not looking.)Some technical aptitude: The swap doesn't require much in the way oftechnical knowledge, but it does require some basic physical skill anddeftness, plus a knowledge of what not to mess with inside acomputer.

This project is not one to tackle if you've never had your hands inside acomputer before. The primary risk -- and it's a real one -- is that you maybreak something. (We mean actually, physically break something, as in snapit off or crack it.) If you do, you will end up with a non-functional pile ofMini parts instead of a working computer.

Overview of CPU Swap

This section provides an overview of the CPU swap process. It is onlyintended to give you a general idea of the process and of the difficultiesinvolved; it is not meant to give explicit step-by-step directions.

Unfortunately, the folks at iFixit.com have not yet produced one of theirexcellent take-apart guides for the Intel Minis, but you can find illustratedguides to this chip swap at these locations:

Meromac Mini: Detailed pictures of the whole process but few wordsMac Mini Intel Core Duo Upgrade Guide: Skips the opening steps ofthe disassembly but covers the critical parts with excellent picturesand good explanations. (This swap uses the Core Duo, but the processis identical for the Core 2 Duo.)My Upgrade to 1.83GHz Core Duo: Also uses the Core Duo insteadof Core 2 Duo. Not as detailed as the two sites above but includesworthwhile cautions about possible trouble spots.

Note: A digital camera is a great aid in disassembly projects like these. Takephotos of each step as you go in case you forget which cable goes where orhow to orient the parts.An overview of the basic steps:

1. Remove the Mini's top case.2. Unmount the Airport antenna, remove four screws, and disconnect

two cables to free the black plastic drive frame, and then lift the frameout with the hard drive and optical drive still in place.The RAM slots and the CPU (covered by a large heatsink) are nowclearly visible on the motherboard. Unfortunately, you need access tothe underside of the motherboard to disengage the posts holding theheatsink in place.

3. Remove one Torx screw and disconnect two cables to free themotherboard, and slide it carefully out the front of the chassis.

4. On the underside of the motherboard, free the four posts holding theheatsink in place, and then remove the heatsink from the top of themotherboard to reveal the CPU.

5. Unlock the CPU socket to free the chip and lift it out, noting theorientation of the chip as you do so.

6. Orient the Core 2 Duo chip, set it in the socket, and lock it in place.7. Clean the old thermal paste from the heatsink, and apply a very thin

layer of new thermal paste to replace it.

Alert: The following step is the point at which the greatest risk of damageexists, in our opinion. Go slowly and carefully.

8. Orient the heatsink, place it on top of the CPU, and push each of thefour spring-loaded posts through the motherboard until they lock intoplace.This step doesn't sound that difficult. But in reality, you're balancing abig square heatsink on top of a small square chip that you have justcoated with grease, and you're trying to keep the heatsink level andproperly oriented while you press down on a spring-loaded post atone corner, attempting to push the post through a hole in themotherboard where it doesn't seem to want to go. And in doing all

this, you're applying force directly to the CPU and the motherboard --the most critical parts of your computer.

9. Once the heatsink is in place, put the Mini back together by reversingthe steps you used to take it apart.

The good news is that with the CPU and heatsink in place, and the Minireassembled, you have nothing left to do but start it up and gloat. The Core2 Duo will be recognized by Mac OS X and System Profiler without anyprompting.

Benchmark Tests

We ran our usual set of benchmarks on the stock Mini and on the modifiedCore 2 Duo Mini. The results below show what we hoped they would -- asubstantial improvement in performance over the Core Solo in all CPU-affected tests. The little Monster Mini is a zippy machine.Test configurations:

Mac Mini, 1.5 GHz Core Solo, 512 MB RAM, 60 GB/5400 RPMhard diskMac Mini, 1.83 GHz Core 2 Duo, 512 MB RAM, 60 GB/5400 RPMhard diskMacBook, 2.0 GHz Core Duo, 2 GB RAM, 80 GB/7200 RPM harddiskMacBook Pro, 2.16 GHz Core 2 Duo, 2 GB RAM, 160 GB/5400RPM Hitachi Travelstar hard disk, 128 MB VRAM

Note: We did test both the Core Solo and the Core 2 Duo with 2 GB ofRAM and an 80 GB/7200 RPM hard disk, but the benchmark scores werenearly identical to those for the stock RAM and hard disk configurations.That's not to say that the RAM and hard disk upgrades aren't a good thing;they are. Their benefits just don't show in these benchmarks.[See our Mac Pro Benchmarks page for more details on the test procedures,as well as comparative data.]

Heat

During our benchmark tests and in other use, the Mini showed no signs ofexcessive heat with the Core 2 Duo installed. Under load (runningCineBench, Xbench, and Geekbench simultaneously), the CPU coretemperatures briefly touched 65° Celsius and the fan reached 4500 RPM,but once the excitement was over, the temperatures and fan speed bothdropped quickly. While doing ordinary web browsing in Safari with a 900MB download running in the background at 155 KBps, the coretemperatures ran around 47° to 49° Celsius, and the fan speed dropped to awhisper-quiet 1500 RPM.

Conclusions

So was the Core 2 Duo swap worth the time and money it took?For the original project Mac, the answer is yes, given that we already hadthe Core Solo Mini and the skills needed to do the installation on our own.For a total outlay of $250, an afternoon's time, and some nervous momentswrestling with the heatsink, we now have a notably fast Mini that retains thequiet good manners of the original.If the Mini had started life as a Core Duo instead of Core Solo, we'd have amore difficult time justifying the outlay required for the chip. But we'd stillbe tempted, especially if we could get one of the 2.0 GHz or faster Meromchips. (And the single unit price of Core 2 Duo chips will undoubtedly dropin the coming months.)And if we had had to buy a Mini to start with, well... With the price of arefurbished Core Solo Mini running around $479 at the Apple Store (whenit's in stock), and the price of the chip still at $250, we're getting close to theprice of a low-end 17" Intel iMac, which includes a screen, keyboard,mouse, and a better performing 3.5" hard drive in its package.We're not done with the Monster Mini yet, though. We subsequently tackledits hard drive system in Phase 2...

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