Many PCs with DDR4 RAM have started going cheap on ebay recently. I don’t know how much of that is due to Windows 11 hardware requirements and how much is people replacing DDR4 systems with DDR5 systems.
I recently bought a z840 system on ebay, it’s much like the z640 that I recently made my workstation [1] but is designed strictly as a 2 CPU system. The z640 can run with 2 CPUs if you have a special expansion board for a second CPU which is very expensive on eBay and and which doesn’t appear to have good airflow potential for cooling. The z840 also has a slightly larger case which supports more DIMM sockets and allows better cooling.
The z640 and z840 take the same CPUs if you use the E5-2xxx series of CPU that is designed for running in 2-CPU mode. The z840 runs DDR4 RAM at 2400 as opposed to 2133 for the z640 for reasons that are not explained. The z840 has more PCIe slots which includes 4*16x slots that support bifurcation.
The z840 that I have has the HP Z-Cooler [2] installed. The coolers are mounted on a 45 degree angle (the model depicted at the right top of the first page of that PDF) and the system has a CPU shroud with fans that mount exactly on top of the CPU heatsinks and duct the hot air out without going over other parts. The technology of the z840 cooling is very impressive. When running two E5-2699A CPUs which are listed as “145W typical TDP” with all 44 cores in use the system is very quiet. It’s noticeably louder than the z640 but is definitely fine to have at your desk. In a typical office you probably wouldn’t hear it when it’s running full bore. If I was to have one desktop PC or server in my home the z840 would definitely be the machine I choose for that.
I decided to make the z840 a build server to share the resource with friends and to use for group coding projects. I often have friends visit with laptops to work on FOSS stuff and a 44 core build server is very useful for that.
The system is by far the fastest system I’ve ever owned even though I don’t have fast storage for it yet. But 256G of RAM allows enough caching that storage speed doesn’t matter too much.
Here is building the SE Linux “refpolicy” package on the z640 with E5-2696 v3 CPU and the z840 with two E5-2699A v4 CPUs:
257.10user 47.18system 1:40.21elapsed 303%CPU (0avgtext+0avgdata 416408maxresident)k 66904inputs+1519912outputs (74major+8154395minor)pagefaults 0swaps 222.15user 24.17system 1:13.80elapsed 333%CPU (0avgtext+0avgdata 416192maxresident)k 5416inputs+0outputs (64major+8030451minor)pagefaults 0swaps
Here is building Warzone2100 on the z640 and the z840:
6887.71user 178.72system 16:15.09elapsed 724%CPU (0avgtext+0avgdata 1682160maxresident)k 1555480inputs+8918768outputs (114major+27133734minor)pagefaults 0swaps 6055.96user 77.05system 8:00.20elapsed 1277%CPU (0avgtext+0avgdata 1682100maxresident)k 117640inputs+0outputs (46major+11460968minor)pagefaults 0swaps
It seems that the refpolicy package can’t use many more than 18 cores as it is only 37% faster when building with 44 cores available. Building Warzone is slightly more than twice as fast so it can really use all the available cores. According to Passmark the E5-2699A v4 is 22% faster than the E5-2696 v3.
I highly recommend buying a z640 if you see one at a good price.
Leave a Reply
You must be logged in to post a comment.