Just a note, as I was recently slightly disappointed when shopping for RAM for a recent Threadripper build:

The current max capacity for Threadripper ECC RAM is 128GB. The largest unbuffered ECC DIMM is 16GB. With an Epyc (or a Xeon) you could used registered memory which is available in higher capacities.

If you went 3990X, you'd be limited to 1GB per thread or 2GB per core. This isn't a showstopper, but could be a bottleneck depending on how RAM-intensive your workload is.

Let me be clear, I'm still quite happy with my recent purchase and build. Threadripper has enabled unprecedented core counts at very low prices.

Along with that, I've not reliably been able to find fast unbuffered ECC ram either. I've seen some 2333MHz stuff but not in 16GB DIMMs and nothing faster actually for sale (I've seen 2400MHz advertised but not actually available). I've got 128GB of 2133MHz and it works fine but it'd be nice to be able to get the extra performance considering how much it matters for the Zen core cpus

Samsung 8gb M378A1K43CB2-CTD and 16gb M378A2K43DB1-CTD

I've only heard about these from buildzoid's overclocking video. https://www.reddit.com/r/overclocking/comments/exnrcz/buildz...

Those don't appear to be ECC capable unfortunately. https://memory.net/product/m378a2k43db1-ctd-samsung-1x-16gb-...

Crucial has 16GB unbuffered ECC at 2666MHz native frequency, available within the last month. It's a very stable overclock at 3000MHz. I think I've got room to move up to 3200. I would love to get to 3600MHz, but that has seemed unstable when I've tried.

CAS latency isn't the best, and tweaking this has resulted in a quite unstable system.

I'm currently running 128GB of this:

https://www.crucial.com/memory/ddr4/ct16g4wfd8266/ct16439854

Neat, that's definitely new and good to hear about. I'm eventually going to upgrade my 1950x and the rest of the system so getting to 3000 would make a huge difference already. I've managed to get my sticks to 2333 but they then report about 3 errors a week, and about 20 a day at 2666. The performance gains from that aren't enough to leave it like that and feel good about it to me.

mind posting your ECC Threadripper build?

I can post a link to a full PCPartPicker list later if you want, or answer specific questions.

It's a 3970X with 128GB (link to RAM in sibling thread) of 3000MHz RAM on a GIGABYTE Aorus Master. No processor overclock. Running Noctua's NH-U14S with one of their high-RPM fans. GPU is nothing special - the cheapest card I could find with DisplayPort 1.4+ and HDMI 2.0+ (for potential dual 4k@60Hz - currently dual 2560x1440@60Hz) - it's a Radeon 550. Boots from NVME and has 40TB raw (20TB usable) spinning disk.

It's a virtualization host and prototyping workstation. I work primarily in data analytics, and it's not uncommon to have prod servers larger than this. I've got enough headroom to realistically test things at scale.