[snerbles]

Personally I use eBay and find the most barebones system I can, then populate the CPU+RAM with components salvaged from e-wasted servers. There are risks with this, as I've had to return more than one badly-bent workstation that was packed poorly.

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So the Dell Precision T7920 runs dual Intel Scalable (Skylake) and has oodles of DIMM slots (24!), but you'll need to use a PCIe adapter to run an NVMe drive. FlexBays give you hot-swappable SATA, SAS too but only if you're lucky enough to find a system with an HBA (or add one yourself). But if you manage to salvage 24x 64GB DDR4 DIMMs, you'll have a system with a terabyte-and-a-half of ECC RAM - just expect to deal with a very long initial POST and a lot of blink codes when you encounter bad sticks. The power supply is proprietary, but can be swapped from the outside.

The T7820 is the single-CPU version, and has only 6 DIMM slots. But it is more amenable to gaming (one NUMA domain), and I have gifted a couple to friends.

If you're feeling cheap and are okay with the previous generation, the Haswell/Broadwell-based T7910 is also serviceable - but expect to rename the UEFI image to boot Linux from NVMe, and it's much less power efficient if you don't pick an E5 v4 revision CPU. I used a fully-loaded T7910 as a BYOD workstation at a previous job, worked great as a test environment.

Lenovo ThinkStation P920 Tower has fewer DIMM slots (16) than the T7920, but has on-motherboard m.2 NVMe connectors and three full 5.25" bays. I loaded one with Linux Mint for my mother's business, she runs the last non-cloud version QuickBooks in a beefy network-isolated Windows VM and it works great for that. Another friend runs one of these with Proxmox as a homelab-in-a-box.

The HP Z6 G4 is also a thing, though I personally haven't played with one yet. I do use a salvaged HP Z440 workstation with a modest 256GB RAM (don't forget the memory cooler!) and a 3090 as my ersatz kitchen table AI server.

[71bw]

    >and a lot of blink codes when you encounter bad sticks

Which sadly happens quite a lot with ECC DDR4 for whatever reason.

    >If you're feeling cheap and are okay with the previous generation, the Haswell/Broadwell-based T7910 is also serviceable

The T5810 is a known machine, very tinkerable, just works with NVMe adapters (they show up as a normal NVMe boot option in UEFI) and even have TPM 2.0 (!!!) after a BIOS update. Overall, they are the 2nd best affordable Haswell-EP workstations after the HP Z440 in my opinion.

    >E5 v4 revision CPU

They are less efficient than V3 CPUs due to the lockdown of Turbo Boost, but then again on a Precision you'd have to flash the BIOS with an external flasher regardless to get TB back.

[snerbles]

Forgot about Dell gimping Turbo Boost on that firmware.

Another route is the PowerEdge T440 (tower server), which does respect Broadwell-EP turbo logic without a reflash. Not quite as quiet as a workstation, though.

[Forgeties79]

Man this so much incredible information in one comment