Back in mid 2019, I picked up an IBM x3550 M4 7914 to use as a VMware host in my home lab. While it didn’t technically have the ‘worst’ Sandy Bridge based CPU ever made (which the E5-2603 v1 SR0LB gets to claim) its dual E5-2609 v1 (SR0LA) CPUs left a lot to be desired. The SR0LA boasts four cores at 2.4GHz, no hyper-threading, 80W TDP, and a measly overall 2,640 (1,101 single-threaded) PassMark benchmark score. Built to a price point, they weren’t exactly going to set the world on fire, performance-wise, but they were what the system had.
In late 2020, I upgraded the M4 with a pair of E5-2620 v1 (SR0KW) CPUs for the whopping price of $6 each. This upgrade boosted the per-CPU core count to 6, added hyper threading, dropped the GHz from 2.4 to 2.0, but did almost double the overall performance, taking the PassMark benchmark score to 5,188, but keeping roughly the same single-threaded performance of 1,110. So while the per-thread performance didn’t jump very much, I was getting a significant overall performance increase. Power consumption did increase to 95W, but that was a small price to pay (literally and figuratively), and I was happy.
In late 2020 I experimented with installing Intel Ivy Bridge-based CPUs, as in theory the M4 should be able to handle them. Right around the middle of the M4’s life cycle, IBM was right in the middle of the sale of the x86 server line to Lenovo and around that time, there were a lot of IBM systems rebranded as Lenovo, vice-versa. The M4 was the former, originally an IBM product that Lenovo re-badged and continued to sell after the sale. What was interesting, however, was that while the IBM documentation for my specific model listed supported processors, it never mentioned the v2 processor series, but the documentation Lenovo did! I figured that while possible, it was extremely unlikely that Lenovo would have changed system at all, much less enough to support the v2 processors, so presumably the M4 supported the v2 processors all along. It was possible there was some kind of firmware lock or ‘supported processor list’ that would prevent it from working, but the potential performance improvement between the two processor generations was too good to ignore, so I looked into getting some v2 processors.
Eventually I was able to pick up a pair of E5-2640 v2 processors for $12 each on eBay. These were pretty nice processors at the time, boasting 8 cores, 2.6GHz, 95W TDP, and benchmark scores of 7628 and 1270. Unfortunately, installing the processors did…nothing. The system wouldn’t post, and the onboard IMM gave strange errors when looking at CPU details. I never could figure if the CPUs themselves were defective, or if there was a problem with the systems compatibility with the processors. Sadly, I put the original 2620 v1’s back into the server and had to eat the cost of the usless-to-me v2 processors, resolving that there was indeed some kind of difference between the IBM and Lenovo versions of the M4 preventing the use of the Ivy Bridge processors.
Time went by, and by 2021 my usage of the M4 had changed drastically. Previously I had it operating almost 24×7, running a series of test VMs and other home-lab stuff. However, after a few very expensive electric bills, I took a hard look at the equipment I had operating and started to consolidate, downgrade, or upgrade (as the case may be) to reduce operating costs. As I was now only powering the system on occasionally, I wanted it to perform as quickly as possible when it was on, so getting more performant CPUs was critical. Knowing that I needed to use v1 processors, I looked for the next best processor that I could cost justify.
So in early 2021, I upgraded to dual E5-2670 v1 (SR0KX) CPUs for the princely sum of $23 each. These were the CPUs with the best performance per dollar that I could justifiably afford at the time. The upgrade again boosted the per-CPU core count, now up to 8, and brought the GHz back up, now to 2.6. From a benchmark standpoint, the overall score jumped to 9077 and the single-threaded to 1476. Not quite doubling the performance of the old 2620’s, but an appreciable gain. It was also an acceptable energy consumption trade off for me, jumping to 115W TDP.
Fast forward again to early 2023. I was browsing eBay and found that compatible processor prices had dropped quite a bit since 2021. I was able to pick up a pair of E5-2690 v1 (SR0L0) CPUs for $11 each. These were essentially the best CPUs that could be fitted to the system, per the IBM supported processor list. Core count stayed the same (8) but now single-threaded GHz jumped from 2.6 to 2.9. The benchmark score jumps from 9077 to 9786, not quite the huge jump like the previous upgrades, but for the price, it’s hard to argue. Again, at the price of power consumption, performance has been improved. 115W TDP is now 135, which again is acceptable for my use case.
These CPUs were fantastic, and gave me almost 3x the performance of the original CPUs in the system, but in the back of my mind, I kept wondering if there was anything more I could do. The v2 processor compatibility bothered me a lot – I suspected at the time I had defective CPUs, but I could never prove it. But now, three years later the v2 processors were so cheap, that it couldn’t hurt to try again.
So I picked up a pair of E5-2630 v2 (SR1AM) processors for $6 each. Ultimately I didn’t care about the performance of the CPUs, I just wanted the cheapest ones I could get to see if they would work. And surprise, they did! I was thrilled!
This success immediately led to another scouring of eBay for a pair of E5-2690 v2 (SR1A5) processors, which I was able to find for $22 each. They were quickly installed and tested as working. These were *actually* the best CPUs that could be fitted to the system. Core count jumped from 8 to 10, and GHz jumped from 2.9 to 3.0. The benchmark scores jumped from 9786 to 13500 (1476 to 1890, single threaded) by going with the Ivy Bridge CPU. It was quite the jump, almost 27%, and for the price, it was hard to argue. Interestingly, TDP went *down* from 135W to 130W.
So at the end of the day, for the price of dinner for two at a two-star restaurant, I was able to get the ‘best’ CPU for this system. On some levels I can no longer hem and haw about if I could eek some more performance out of the system – it’s the best CPU available. By pure benchmark numbers, the system is about 5x more powerful than its original configuration, at the expense of roughly doubling the electrical consumption and thermal output. So far I have not yet noticed any issues or concerns. Time will tell.
In theory, there are the 12-core Ivy Bridge processors, but they trade off the extra two cores for a GHz reduction. The E5-2697 v2 has a 2.7GHz clock, and a 14362 benchmark score, but the single threaded performance is lower than the 2690 at only 1807. As of the writing of this article, they are selling for about $35 each, and aren’t listed as supported by either IBM nor Lenovo. For my purposes, single-threaded performance is more important than adding the additional cores.
My venerable M4 is starting to get quite old – originally released in 2013, and obtained by me in 2019 – but it still fills my needs for an occasional VMware host. ESXi 6.7U3 is the last release officially supported by VMware on the box, but it fills my needs adequately for now. With that said, I think my M4’s upgrade days may be at an end.