Step by Step: Mac Pro Processor Upgrade

My primary workstation is a 2009 8-core Mac Pro.  When I purchased the machine about two and a half years ago, I knew I wanted eight cores but at the time I could only afford the 2.26GHz option and 6GB of RAM.  As one of Apple’s few remaining “upgradeable” line of computers, I hoped to upgrade the processors and RAM in the future.  Back in June, with the impending launch of Final Cut Pro X and the increasing number of other high-performance applications that seemed to be running slower and slower on my Mac Pro, I knew the time had come to perform the upgrade I had planned.

I’d like to take the time to mention here that everything discussed in this article, except for the RAM upgrade, most definitely voids your warranty.  In my case, the warranty had expired so I had nothing to lose in that department.  But if you choose to follow my lead and upgrade your own Mac Pro, please understand that you do so at your own risk.

Now, down to business.  The upgrade would come in two phases: RAM and CPU.  The RAM would be simple, but I knew the CPU upgrade would be a challenge and that there was a risk that I could irrevocably damage my Mac.  Considering the options, I decided to accept the risk and move forward with the upgrade.

Inside the Mac Pro

Apple’s support article explains everything you need to know about RAM upgrades.

I started with the easy part, and ordered 24GB (6x4GB) of RAM from Other World Computing.  The price at the time was $320.  This was back in June.  Prices have now dropped even further, and the same 6x4GB configuration of RAM now costs only $244 as of the date of this article.  The Mac Pro RAM is surprisingly easy to upgrade, second in ease perhaps only to the Mac Mini.  It is a completely tool-less process and requires only removing the side panel from the computer, and then removing the processor tray from the bottom.  Apple Support Article HT4433 helped explain the process, but for those familiar with hardware upgrades it is a very straightforward procedure.

For the processors, I decided to go “all out” and get the highest performance processor I could find.  That would be the Xeon W5590 at 3.33GHz.  These processors still retail at a ridiculously high price, between $1500 and $1800 each, but there is thankfully a robust market of used processors on sites such as eBay.  I admit that I was a bit hesitant to purchase used processors, but after some research I found a seller with excellent ratings and an equally excellent price: $1200 for the pair of processors.  They may be used, but at 66% off the retail price, I couldn’t say no.

Intel Xeon processor

The Intel Xeon Processor.

The first challenge I faced was improper tools.  The Mac Pro’s CPU heatsinks are surprisingly held in place with common 3mm hex screws.  The only problem is that the screws are recessed about three inches into the heatsink, and I had no hex wrench long enough to reach the screw.  A late-night trip to the local hardware store solved the problem, and I recommend purchasing the longest hex wrench set you can find before beginning this process. 

The screws themselves are spring-mounted, so simply loosen them slowly until you feel them pop up.  Once all four screws are removed per heatsink, carefully lift the heatsink up, detaching it from the connector on the logic board that controls fan and thermal settings.  Be careful to note that the processor will likely be stuck with thermal paste to the bottom of the heatsink and will lift off when you remove it.  Quickly turn the heatsink upside down to prevent the processor from coming loose and falling (although in my case the thermal paste acted almost as glue and it took quite a bit of force to detach it).  Repeat for the second heatsink.  Be sure to make note of which heatsink goes to which socket, as they are not interchangeable. 

With the heatsinks and processors removed, I set about cleaning off the old thermal paste from both parts.  There are specialized cleaners for this task, but I’ve found that a clean microfiber cloth and rubbing alcohol do the job just fine.  Just be careful not to overuse the rubbing alcohol and have some spill over onto other parts of the system.

Lidless Mac Pro CPU

A lidless CPU like those in the 8-core Mac Pro.

With the parts cleaned, I opened the package containing the new processors and the first thing I took note of was the drastic difference in appearance between the chips.  The stock chips used on the 8-core Mac Pro are lidless, meaning the metal cap used for protection that is recognizable on most chips is not present and the core of the chip is directly exposed.  I feared this may cause two issues: first, because the chips I was installing were lidded, the extra height of the lid might not allow the heatsink and CPU to sit properly in the socket; second, the Mac Pro was thermally designed for lidless chips and the lidded chips might cause temperatures to rise too high.  Both concerns proved to be immaterial in the end, although special consideration had to be paid to ensure that this was the case.

I started with “CPU A” and placed the processor into the socket.  After applying new thermal paste (I used Arctic Cooling’s MX-2) to the CPU, I slowly lowered the heatsink into place, ensuring that the fan/thermal connector was lined up properly.  I then began to slowly tighten the hex screws that hold the heatsink in place.  Because the new CPU was slightly thicker than the old one due to its lid, I wanted to tighten the screws a little at a time until I was sure that the heatsink was tight and secure, but not so tight as to cause damage to the socket.  This turned out to be about five turns of each screw, performed corner-to-corner to ensure that one side did not over-tighten and skew the chip’s orientation.

The 8-core Mac Pro can run with just a single processor installed, so I quickly put the computer back together to test my installation before attempting to replace the second CPU.  To my relief, the system booted up just fine and System Profiler showed that a single 3.32GHz (not quite sure why the processor reports itself as 3.32 instead of 3.33GHz) processor was installed.  Satisfied, I shut down and dismantled the computer again to install the second CPU, repeating the steps above.

With both CPUs installed, I booted the machine and again it booted fine, but I noticed a problem: the fan on the second CPU (identified in the system as “Booster B”) was running at full speed despite normal temps on the processor.  I was quite concerned that I had damaged something and began fearing for the worst: a lifetime of listening to a jet engine under my desk (those with Mac Pros know just how loud our machines can get when the fans go full speed).

I shut down and disassembled the system again.  I decided to try removing and reattaching the second heatsink in hopes that it would solve the issue.  Sure enough, as I reattached the heatsink I noticed that the fan/thermal connector “clicked” into place a little better than it had before and when I rebooted the system, the problem was solved.


My “new” Mac Pro.

With both processors installed, I decided to do some stress testing to ensure that both the used processors were still fully operational and that I hadn’t messed up anything else during installation.  There are many ways to stress test a Mac but my new favorite method is using Primate Labs’ cross-platform benchmark tool GeekBench.  Starting with version 2.2.0, GeekBench includes a stress test option in the “Benchmarks” menu.  I let that test run for several hours and thankfully received no errors.  My other previously mentioned concern was operating temperatures and I was happy to see that my temperatures only rose about 3℃ over the operating temperatures of the stock processors, a noticeable but completely acceptable result.

Now confident that the hardware I installed was “good,” I set about to find out just how much performance I had gained for my money.  Turning again to the aforementioned GeekBench, I ran the test three times and averaged my results.  Before the upgrades, my GeekBench Score was a respectable 13958.  After the upgrade, my score jumped to 20643, an approximately 48% increase in performance.  By contrast, a top-of-the-line Mid 2010 12-core Mac Pro at 2.93GHz with 24GB of RAM scores 24730, but costs $7300.


My upgraded Mac Pro goes a long way towards bridging the gap between a base 2009 model and a top-end 2010 model.

In the end, I spent about $1500 and brought my Mac Pro back up to speed with the current generation.  The performance increase has been noticeable in everything from day-to-day usage to Final Cut Pro X rendering.  Considering the high cost of a 2010 Mac Pro (and whether we’ll even get a 2011 Mac Pro), I am quite happy with the end result.  The only tools needed are a long 3mm hex wrench, some thermal paste, and time.