The two heatsinks on the Mac Pro aren’t interchangeable, so keep track of which one came from where and don’t try to force their installation if they don’t fit properly.

After we completed the swap, we powered the machine on and were met with the worst sound: fans that didn’t spin down. The Mac Pro refused to POST and forcing it to turn off revealed a CPU A Temperature Overheat warning LED on the motherboard.

Removing the CPU_A heatsink revealed the problem:


CPU_B was fine, but CPU_A was far from it. While there are no pins to bend/break on these LGA CPUs, if anything goes wrong the socket is toast. In this case, both the socket and CPU were beyond saving.

To date I’m not sure what went wrong, but I have two theories. Unlike desktop Nehalem motherboards, there is no clamp that holds the CPU in place. There’s a chance that during the heatsink installation that the CPU moved slightly and shorted as soon as it got power.

The other theory is that I somehow over tightened the heatsink on CPU_A. Remember, the chips I used had heat spreaders, the ones they were replacing did not. The added thickness of the heat spreader could have helped push the CPU too hard against the pins in the socket, causing some of them to move out of place.

Regardless of the how, what remained was that I now had a dead Xeon and a dead Mac Pro processor board on my hands. The CPU I could always replace from my stash, but I don’t keep many Nehalem Mac Pro processor boards in my parts closet. This would require a trip to the Apple store.

And if you’ve ever walked into an Apple store holding a Nehalem Mac Pro processor board, you’ll get some looks.

Thankfully, the folks at the Crabtree Valley Mall Apple Store in Raleigh, NC are AnandTech readers and quickly understood what had happened. They ordered the replacement part and I waited. If you’re curious, it’ll cost a bit under $400 to replace the processor board in an 8-core Mac Pro provided you allow Apple to keep your dead board.

The new board and its accessories

It’s been years since I’ve killed a processor and this would be my first LGA socket death, so I was admittedly nervous once I had the new board in hand. I went in and tried to replace the chips again, this time under tightening all of the hex screws on the heatsinks just to be safe.

I mounted and dismounted each heatsink three times before committing to the install. Nervously, I hit the power button.

I had good news and bad news.

The bad news, the fans were spinning at full speed. The good news? The upgrade worked. Initially I didn’t tighten the heatsinks enough so some of the memory channels weren’t working, but a couple more spins of the hex key and I was in business.

The fans spinning at full speed were caused by the thermal sensor on one of the heatsinks being dead. It looks like it died when the first CPU shorted out. The folks at the Apple store had to order me a replacement heatsink as well.

After the smoke cleared and my embarrassment subsided, I had an upgraded Nehalem Mac Pro.

I started with a pair of 2.26GHz Xeon E5520s and ended up with a pair of 2.93GHz Xeon X5570s.

Gaining access to the processors is far easier than the previous generation Mac Pro, but you have to exhibit more care in physically replacing them. The fact that the CPUs I used had integrated heat spreaders hasn’t caused any problems either. Temperatures are well within reasonable limits, the fans are just as quiet as before and Turbo mode still works.

Upgrading the CPUs in the Nehalem Mac Pro Upgraded Mac Pro Performance


View All Comments

  • wackazong - Wednesday, September 9, 2009 - link


    this may be the right place to ask: What's the difference between the Xeon and the (much cheaper) i7 processors? Couldn't you put an i7 into a Mac Pro?
  • sdevenshire - Saturday, August 29, 2009 - link


    I purchased a 2xQuad core mac in Jan 2008 and I would like to upgrade the cpu to the new Nehalem. Apple suggested it could be done but they don't do it. I contacted a number of Mac repair places and they said it can't be done. I realize that upgrading the cpu probably means upgrading the motherboard, but that's fine with me.

    Any suggestions on where I could get this done or where I might get instructions for doing it myself?

  • 529th - Thursday, July 30, 2009 - link

    If you’ve read our Nehalem articles you’ll know that each chip has three 64-bit wide memory controllers, thus you’ll want to install DIMMs in triplets. You can install four DIMMs, but accessing memory in the fourth module will be slower - something you’ll never notice if you’re wondering. ???

    This is hindering me from buying a 4 channel UD3R X58 board. My main goal of an i7 build is for editing AVCHD files through Premiere Pro CS4. Being that tri channel will get me 6g and PP CS4 likes more memory, will adding memory to the 4th module screw things up?
  • newrigel - Tuesday, July 28, 2009 - link

    Man, take your hackysack and go buy some laundry soap to clean the crap out of your drawers! You guy's talk about a couple thousand dollars like it's buying a damn house or some huge purchase LOL!
    Macs are really cost efficient and yes... PC's are cheaper but who gives a damn! If you want to be cheap... be cheap! Hackintoshes (LOL) are just that... a POS and your getting what you pay for! You cheap asses probably hit your ol' ladies up for gas money to get to work hehe...
  • ditchmagnet - Monday, July 27, 2009 - link

    Just for fun I went to apples site and customized the mac pro, I just maxed out the hardware choices and then went to newegg and priced out an equivalent PC (Server board, with the same CPUs and everything except more RAM)
    Total for the apple including shipping and tax is over $20,000
    the newegg build is under $9,000
    I bet my 920 build at 4.5ghz is faster than the mac pro though, and all for under $1000
  • moltentofu - Tuesday, July 21, 2009 - link

    wander over to the egg and buy a lian li. No flashy lights really, no idiot clear side panels. For some reason the hard drive access light and the power light are different colors on mine though.

    You can get a combo case with a seasonic 550W power supply with it. I put a phenom II x4 3.2Ghz 16 Gigs of RAM and a 1 Gig 4870 in there with aftermarket cooling all around (air not liquid) and it cost me 900 bucks - all from the egg.

    If you think you're going to find performance arbitrage basically anywhere in the market you couldn't be wrong-er. Just pick your price/performance point and stick to it.

    Thanks for the awesome reviews as usual Anand!
  • moltentofu - Tuesday, July 21, 2009 - link

    With one big 'ol caveat to the arbitrage thing and that is: building your own system really does seem to be cheaper right now, and also I can't find component setups in the big name companies right now that make me quite happy.

    I miss when Dell Outlet used to be affordable. I'm afraid these Macs are just waaay out of range of my meagre salary.
  • fmaste - Monday, July 20, 2009 - link

    Everybody talks about how expensive the Mac Pro is, but, has somebody compared with other brands? Look at this:

    I customize two Dell Precision Workstations with the same components as the base configurations Apple offers for the Mac Pro.
    The results!!

    Mac Pro Quad-Core: $2,499.00
    Dell Precision T5500: $3,427

    Mac Pro 8-Core: $3,299.00
    Dell Precision T7500: $3,427

    Both with the same processors, same amounts of memory at the same speed.
    The only difference is instead of a NVIDIA GeForce GT 120 with 512MB you get a 256MB NVIDIA® Quadro® NVS 295. And that Dell options have hard drives with less capacity, 500GB vs 640GB. I also added the second Gigabit Ethernet card to both Dells. Dell has no bluetooth option and you may need to add a sound card to them.
    Remember, you get a more expensive PC with windows Vista and an ugly chasis.
  • fmaste - Tuesday, July 21, 2009 - link

    And here is HP

    Mac Pro Quad-Core: $2,499.00
    Same specs configurable HP Z800 Workstation: $3,942.00

    Mac Pro 8-Core: $3,299.00
    Same specs configurable HP Z800 Workstation: $3,702.00
  • excalibur3 - Friday, July 17, 2009 - link

    So when you hypothetically created your i7 hackintosh, what were it's specs? I'm thinking about doing this (as a thought experiment only of course) and I'm wondering what such a system would price out. How would I know what motherboard to use to be compatible? Reply

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