Upgrading a server for the first time in 10 years, so I’m a little out of the loop. I was surprised to find that the RAM I bought didn’t fit.
This is my first time dabbling in ECC RAM, so I figured there was some minor detail I missed when purchasing, but I eventually came across the data sheet for this stick, and the dimensions given don’t match the measurements I’m making. The tip of the caliper should be in the middle of the notch at 68.1mm.
What’s more is that the dimensions in the data sheet seem to match the dimensions on my motherboard. What’s going on here?
[SOLVED] I and Kingston are morons. I ordered RDIMM instead of UDIMM. The Kingston datasheet gives the wrong dimensions.
You try flipping it around? The notch isn't centered
Nope. Doesn't work either way. The stick is 133.36mm wide which matches the datasheet, so measured from the other side, the notch should be at 65.25mm. Still not ~~68.1mm.~~ 62.67mm that I measured.
133.36-65.25 = 68.11
Are you sure you zeroed out your calipers correctly before taking the measurement in the photo?
My bad. Used the wrong numbers. The notch as measured is 62.67mm from one side and 70.70 from the other.
I think that matches the RDIMM keying although that information is oddly hard to find online.
https://www.mouser.com/datasheet/2/671/ddr5_rdimm_core-3310292.pdf
Page 24 has dimensions but you have to do some arithmetic to actually get the slot center of 62.8mm and 70.55mm
So I think the kingston spec sheet has the wrong drawing that shows UDIMM dimensions.
I think you need to return the RDIMM and get UDIMM, or switch motherboards.
Right? I was hoping for like a wikipedia page with the dimensions of every kind of DIMM. Might have to make one...
So I think you're right. The only explanation is that I ordered RDIMM instead of UDIMM and that Kingston messed up.
I just double checked, the compatibility checker suggested the -EU variant, but I was looking at -ER. (Un/Registered).
It doesn't help that ECC and registered get interchanged a bit it seems.