I’m a theoretical scientist and programmer and a little challenged practically speaking, so I hesitated about this upgrade. After viewing OWC’s very helpful video and some others - and doing a lot of prep around tools, a clean work area and static precautions - I decided to go ahead.
Several points to note. First, my 4 year old Mac Pro was caked with dust. You don’t get a sense of this from the video which features a pristine machine. Be prepared for this possibility with q-tips, compressed air and extra isopropyl alcohol.
Second, if like me you’ve not done this before, patience and deliberation is key. Some screws and connectors can be a little stiff - I saw evidence of loctite I think - but force them gently and there’s no problem.
Third, when I got to the second, inner set of 4 Torx 10 screws that secure the spring retainer that tensions the CPU I suddenly noticed they were perfectly flat, smooth round bolt heads. What?! It took some time but I discovered Apple had finished this inner set perfectly with color-matched tape! This was not hard to crack and remove, but held me up for a good half-hour.
Fourth, that spring retainer is *strong*. The thermal compound I selected - not the grease in the kit - emphasized absolute cleanliness of the heat sink and CPU cap, so at first I tried to reseat the first two screws without pressing on the CPU. This was a mistake. You really do need to support the assembly well from behind. Luckily I sourced extra (70%, medical grade) isopropyl wipes for the earlier stages of cleaning the heat sink and old CPU, keeping OWC’s supplied 99.9% wipe for a final clean-down prior to applying the grease.
It really is important to use the high purity isopropyl alcohol at this last stage as it dries much faster and reduces the chance of dust contaminating the final seal. The 70% wipes include water which means longer dry times.
Now not quite two days later I’m very happy with this upgrade. The 8-core Xeon does a lot of clever management, running around 2-3 cores under normal, unstressed operation. Single core speed (with Geekbench) has dropped only slightly from my original 4-core CPU. System load is about halved. Then when needed, such as compiling a lot of source with Xcode everything switches up and compile times are lightning fast. I anticipate similar gains when running large simulations: these can keep the Mac Pro running for hours and this is where its ability to dissipate heat and let the Xeon run without throttling keeps this Mac very viable even in 2020