1x8GB single rank 2666 (might have been a 2×8 kit since it came with my prebuilt)
CPU-Z says Nanya, Thaiphoon says Nanya A-die (I don't trust them, though). Serial numbers on the ram don't really come up with anything on google.
I've been tying to overclock it, but I don't know the max daily voltage it can run because I can't find the IC. 1.35v doesn't do loose subtimings (safe preset in the DDR4 guide with tRFC and tREFI on auto spits out errors after 40m of OCCT GPU+RAM even though it passes TM5 anta extreme and absolut overnight)