Crucial 64GB (4 x 16GB) 288-Pin DDR4 SDRAM ECC Registered DDR4 2133 (PC4 17000) Server Memory Model CT4K16G4RFD4213

Pros: - Low profile. Clears my 2U heatsink, barely. :) - Plug-n-Play into a Supermicro mobo running at 2133 Mhz out of the box.

Cons: Expensive: It was $550 when I bought it in 3rd quarter 2015.

Overall Review: Installed into an Supermicro MBD-X10SRA-F.

Pros: -Stable, hi-density, ECC server memory -Put 8 of these in a an Asus X99-WS/IPMI motherboard for 128GB RAM without issue, running stable now for a month with ESX 6.0 -DDR4 speeds and performance -Right now the only game in town if you want >65GB RAM in DDR4 on consumer boards with only 8 slots

Cons: -Expensive -Made in China

Overall Review: passed memtester

Pros: Works on my Asus X99 WS N with Xeon E3 1650 v3.

Cons: Doesn't look to be overclockable.

Pros: Never gave me any trouble with my Asrock X99 WS-E + Intel Xeon E5-1650 v3 Haswell-EP 3.5GHz. Tested in windows 10 and ubuntu 15.10 (both x64) I use this with a massive noctua NHD-15 cooler with no space issues.

Cons: Expensive...hopefully you get what you pay for.

Pros: This is registered ECC server memory not unbuffered.

Cons: It does not state the type of ECC memory in the specifications. I ordered this memory assuming it was unbuffered since it did not say it was registered. I was wrong.

Overall Review: I'm sure it's good memory since it's from a good name in memory.