HP Z640 and E5-2696 v4
I recently decided to upgrade the CPU in my workstation, the E5-2696 v3 CPU was OK (passmark 2045 for single thread and 21,380 for multi thread) [1] but I felt like buying something better so I got a E5-2696 v4 (passmark 2115 and 24,643) [2]. I chose the E5-2696 v4 because I was looking for a E5-2699 v4 and found an ebay seller who had them at $140 but was offering the E5-2696 v4 for $99 and the passmark results for the two CPUs are almost identical.
After buying the CPU and waiting for it to be delivered I realised that the Z640 doesn’t include it in the list of supported CPUs and that the maximum TDP of any supported CPU is 145W while according to passmark it has a TDP of 150W. I looked for information about it on Intel ARK (the official site for specs of Intel CPUs) and discovered that “The Intel® Xeon® Processor E5-2696 v4 is designed to be used by system manufacturers (OEMs), and this means they can modify its specifications depending on the system where it will be implemented” and “The processor does not have an ARK page for this reason, since it has no standard specification from Intel, so depending on the original system, it is necessary to contact that system manufacturer for information” [3]. That’s the official response from an Intel employee saying that there are no standard specs for that CPU!!!
Somehow I had used a E5-2696 v3 for 3 years without realising that the same lack of support and specs applies to it [4]!
I installed the new CPU in another Z640 which had a E5-1620 v3 CPU and it worked. I was a little surprised to discover that the hole in the corner is in the bottom right (according to the alignment of the printed text on the top) for all my E5-26xx CPUs while it’s in the top left on the E5-1620 v3. Google searches for things like “e5-2600 e5-1600 difference” and “e5-2600 e5-1600 difference hole in corner” didn’t turn up any useful information. The best information I found was from the Linus Tech Tips forum which says that the hole is to allow gasses to escape when the CPU package is glued together [5] which implies (but doesn’t state) that the location of the hole has no meaning. I had previously thought that the hole was to indicate the location of “pin 1” and was surprised when the new CPU had the hole in the opposite corner. Hopefully in future when people have such concerns they can find this post and not be worried that they are about to destroy their CPU, PC, or both when upgrading the CPU.
The previous Z640 was one I bought from Facebook marketplace for $50 in “unknown condition” in the expectation that I would get at least $50 of parts but it worked perfectly apart from one DIMM socket. The Z640 I’m using now is one I bought from Facebook marketplace for $200 and it’s working perfectly with 4 DIMMs, 128G of RAM, and the E5-2696 v4 CPU. $300 for a workstation with ECC RAM and a 22 core CPU is good value for money!
There are some accounts of the E5-2696 v4 not working on white-box motherboards including a claim that when it was selling for $4000US someone’s motherboard destroyed one. The best plan for such CPUs is to google for someone who’s already got it working in the same machine, which means a name-brand server. That doesn’t guarantee that it will work (Intel refuses to supply specs and states that different items may work differently) but greatly improves the probability.
This system has the HP BIOS version 2.61, note that the Linux fwupd package doesn’t seem to update the BIOS on HP workstations so you need to manually download it and install it. There is a possibility that a Z640 with an older BIOS won’t work with this CPU.