DIMM vs. Udimm vs. Rdimm vs. Sodimm vs. Cudimm: What's the Difference?

This isn’t really a deep dive into the tech, it’s just an SEO placeholder for a company that sells memory modules.

That aside, people usually learn about RDIMM the hard way when they need to get ECC unbuffered RAM for something like HEDT/workstation or tower server Xeon/i3/Ryzen with ECC support but buy the cheaper RDIMM instead of the ECC UDIMM modules only to figure out they don’t work!

HEDT has disappeared. It's just server platforms with RDIMM now.

Not true, the W790 chipset is purely for HEDT/workstations, distinct from the sapphire rapids server line. AMD also has an entire separate HEDT socket, sTR5 for threadripper CPUs. HEDT is alive and well!

HEDT as a consumer product segment distinct from the workstation segment is pretty close to dead. Intel hasn't introduced a new HEDT socket since 2017 and hasn't launched any new CPUs for that platform since 2019.

AMD's Threadripper line has been inconsistent; the 5000 series was all Threadripper PRO parts, then last year's 7000 series brought back the non-PRO Threadripper options. But even the entry-level Threadripper CPUs and TRX50 motherboards available today are less affordable than HEDT systems were eg. 15 years ago. The high core counts available in mainstream desktop sockets have shifted the boundary between that segment and HEDT, and as a result there aren't good options to step up to a platform with more IO capability without also stepping up to really high CPU core counts.