Upgrading CPUs of a Mac Pro to Quad Core Xeons

Reassembling and conclusion
Unlike Core 2 Duo, Xeon processors are pinless.

As shown on the photo, there are notches marked on the side on the CPU to prevent improper installation. Install the new Quad Core Xeon 5355 processors then lock them in their sockets.

Before reassembling, do not forget to add fresh thermal paste on the contact surface. The surface being larger than the one of a Core 2 Duo, one will have to add more thermal, use about 1/6 of a standard Artic Silver tube per CPU.
You can then start reassembling, starting with the lower heatsink, and do not forget to re-plug temperature sensor.
Technically, it is not difficult, once you have a long hexagonal screwdriver. As usual, we are not responsible for any damages or issues that may arise while you try to repeat the procedure described in the previous pages.
We will of course publish another article to analyse the performance gain that can be measured when doubling Cores powering a Mac Pro. Despite its 8 cores draining much more power 240W vs. 160W for the original Xeon, the Mac Pro remains a silent computer.
Of course, OSX can already handle and manage all cores, even though the system can not assign the proper name for the CPU as shown below.