How to determine the rank (config) of a SODIMM before buying?

[Stereodude]

I have an AMD Zen 3 based mini PC with 2 DDR4 SODIMM slots. Everything I've read says dual rank memory has the best performance in AMD systems. How can I determine the rank of a given SODIMM before buying? I'm trying to get a 16GB (2x8GB) 3200MHz kit.

Crucial will list the rank config, but for some they show it can come in 1x8, 1x16 and 2x8. So no idea what I'll get when buying. However, the oldest production were likely the 2x8 with the newest being the 1x16. My best understanding is that counting the chips on the SODIMM should be a good indicator. A SODIMM with 16 chips should be a 2x8 config. I know only having 8 chips or 4 doesn't guarantee that it's single rank, but makes it possible or perhaps likely.

Even chip count doesn't quite solve this... Finding a vendor who will show a picture of the exact RAM they're going to ship instead of a stock image is proving rather difficult too.

Why is this so hard? It seems like only by buying 32gig SODIMMs (DDR4) are you basically guaranteed to get dual rank memory, but I have no need of those and they're quite expensive...

 

[alex_stief]

You can't.
Not enough people care, especially for SODIMM.
Though for recently produced 8GB DDR4, chances are very high you get single-rank.

 

[Stereodude]

You can't.
Not enough people care, especially for SODIMM.
Though for recently produced 8GB DDR4, chances are very high you get single-rank.

That's what I figured.

Am I right that a SODIMM with 16 chips on it should be dual-rank though?

Edit: Could a 16 chip SODIMM be 1x16?

 

[RolloZ170]

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Am I right that a SODIMM with 16 chips on it should be dual-rank though?

afaik yes on DDR3.
DDR4 is also avail. in x16 conf. 4 chips single rank, 8 chips dual.

 

[Stereodude]

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afaik yes on DDR3.
DDR4 is also avail. in x16 conf. 4 chips single rank, 8 chips dual.

I think that means an 8 chip DDR4 SODIMM could also be dual rank (or not)...

Can a 16 chip SODIMM DDR4 be single rank? (1x16?)
Is trying to find 16 chip SODIMMs my best bet to maximize the likelihood of getting dual rank SODIMMs?

 

[RolloZ170]

Can a 16 chip SODIMM DDR4 be single rank? (1x16?)

no, but a 8 chip x16 is dual rank(2Rx16)
on samsung,micron, and SK-Hynix OEM SO-DIMM this is printed on the Label.

 

[Stereodude]

no, but a 8 chip x16 is dual rank(2Rx16)
on samsung,micron, and SK-Hynix OEM SO-DIMM this is printed on the Label.

Thank you... I hadn't thought to be looking for single sticks of OEM memory. I found quite a few listings on eBay for 16GB 2rx8 DDR4 3200Mhz SODIMMs.

Edit: I used the OEM part numbers on the SODIMMs that I found earlier to find more listings for them. I also discovered that eBay's search returns lots of non-matching results to a search query. I haven't really found dual rank OEM SODIMMs that are 8GB. FWIW, I didn't find any 8 chip dual rank 16gb DDR4 3200MHz SODIMMs either. All the ones I found have 16 chips per SODIMM.