I picked up a 6-core Mac Pro (Late 2013) a couple of years ago to replace my ancient Core 2 Quad Hackintosh. I upgraded it with 64 GB of RAM and a 960 GB SSD, hooked up a pair of 27″ monitors and an external Thunderbolt 2 drive box, and went to town. And it was pretty good in that configuration for a combination photo processing and software development platform. (The Hackintosh got recycled into a Network Attached Storage system, for which purpose it was overkill. But it was paid for.)
But anyone who knows me knows that I would have to do something more significant to really make it mine. I tinker, therefore I am is my creed.
A CPU upgrade was in order. The Mac Pro uses one of Intel’s Ivy Bridge EP series Xeons. The obvious choice was a Xeon E5-2667 v2 – it would “turbo boost” faster than my 6-core and had more than double the L3 cache. Anything with more cores wouldn’t run as fast under single-thread loads. But Intel’s price for a new one is steep, in excess of US$2000! I had to wait for them to get cheap on the used server parts market.
That time is now. At this writing (November 2018), they can be had for less than US$250 from reputable sellers on eBay. Mine set me back US$224.50, shipping included.
Swapping CPUs was straightforward, if tedious; but then I already had a bunch of Torx drivers and some leftover thermal compound from the Hackintosh and other PC experiments. The job looks scarier than it is in reality. Of course, if you don’t know which end of a Torx driver to hammer on, best to leave it to someone more confident in their abilities.
I screwed it back together, and while running a CPU-intensive test (updating MacPorts), quickly discovered I had disconnected the one fan in the Mac. OOPS!! Fortunately that turned out to be a cable that had pulled out of its ZIF connector, and was fixed in short order.
And it was then I determined that Apple’s fan speed curve was biased far more towards quietness than coolness. CPU core temps would climb up to 84°C and beyond under full load. If you plan to really exercise your 8-core workhorse with CPU-intensive loads, I strongly suggest you get at the very least a temperature monitoring app, and ideally an app that lets you customize the fan speed settings. I found Macs Fan Control and TG Pro to work nicely; I prefer TG Pro because it offers more temperature readings and more control over the fan speed. It’s also instructive to run Intel® Power Gadget to watch what your CPU is doing in real time, how fast it’s running, how much power it’s burning, and how hot Intel thinks the CPU is.
The PC overclockers use Prime95 as a stress test, so once I had fan control, of course I had to do the same. I discovered that even with the fan at full speed, the Mac Pro’s cooling system was only adequate to bring the CPU down to 79°C at full load. Intel specifies a max package temperature of 74°C, and mine was missing the mark by at least 5°C in a 22°C room. I’d love to see that come down a few more degrees. But it didn’t seem to hurt anything, and ran fine for 2 hours under those conditions.
Since Prime95 and recompiling GCC are the two most CPU-intensive tasks I can think of, I’m confident nothing will ever stress this Mac Pro any harder. So I’ve probably got plenty of safety margin for more prosaic tasks, like processing a few hundred photos.
If you’ve got a 4- or 6-core “trashcan” Mac Pro, and you’re not afraid to tear it apart, I highly recommend this 8-core CPU upgrade. But monitor your temperatures and dial up a more aggressive fan profile, or you may wind up burning up your new “hot-rod” CPU.