Nice server. The free shipping just about makes it worth the price.
Has anyone done an OBO? I'd go in for $225 and wouldn't go any higher than... $275 maybe if it was me (figure about $50-$75 for shipping these days).
Supermicro 2U systems that hold multiple GPUs go for about $300-$350, sometimes. Have to set a price alert for them.
Dual Supermicro X10 motherboards (v3/v4) with LSI SAS3 8-port controllers, are available now for $250. Though, I don't expect their stock to last long as X10 dual CPU mobos are getting harder to find at a low price (inflation sucks for us buyers in eBay, in addition to chip shortages).
Other dual X9 (V1/V2) systems you can get for $100, free shipping.
The only other bit of info to share is that E5-2600 V3/V4 CPUs have taken a pretty big price drop in recent months, greatly helping populate these beasts with 16 high speed 3.4G base clock cores, and all Turbo to 3.7Ghz, and single core turbo to 4Ghz! for about $140 for both 8C chips. The premium chips still command $150-$200 each though. Still better than the $400 prices they were commanding at the beginning of 2022.
E5-1600 and E5-2600 V1/V2 chips have had the bottom drop out with them. Full blown 12C highest end CPUs, E5-2697s, $60.
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Then again, my $200 AMD Epyc 7551 (there's one for sale right now in the FS forum) @ 2Ghz benched 27% faster, per core, than my E5-2670 V2 and 18% faster, per core, than my E5-2650 V4 (which is clocked higher).
And I have 32C, and 64T, that I don't have to disable HT for (to bypass Spectra/Meltdown in Intel). This is what is killing the performance of the V1-V4 series (and other Intel's): Linux and Microsoft "mitigations" around Meltdown/Spectra is to test if the CPU is vuln on boot, and patch the kernel if the microcode has not been patches. This hurts Intel - a LOT. Disabling HT is how you get the performance back, but at the cost of no HT.
Also, with the Epyc first gens you get M.2 PCIe slots, 4x4x4x4 mix of bootable ports, and even PCIe 4.0 if you are lucky to find a Gen 2/3 board that runs Gen 1 (AsRock Rack to the rescue!! Yes, there are a few AsRock Rack Gen2/Gen3 boards that can be bios flashed to run Gen 1 @ PCIe 3.0). Not to me too, OCULink, aka U.2 connections.
So if it comes down to cost-vs-performance, the Epyc 7001 first gen are really coming down in prices.
It's just the motherboards that still command your first-born son, left testicle, right kidney, and both legs in prices. Narrow down the board you want, set a max-price eBay price alert for about what you want to reasonably pay for, and wait... It took me 7 months until I got a board, for $250.