I am trying to pick ram for my laptop. I can see these types of ram on the site.

Ddr4 2133 pc4 17000
Ddr4 2133 pc4 17000s
Ddr4 2133 pc4 17000u
Ddr4 2133 pc4 17066r
Ddr4 2133 pc3 17066

What does the latter at the end or lack of it mean? Which one should I choose? Also, about the 3 or 4 after pc. What is it supposed to mean? Is bigger number better?

  • Voting to close: echnical support request — Questions asking about troubleshooting hardware or technical support for hardware are off-topic for Hardware Recommendations because the site is here to provide pre-purchase hardware recommendations and to recommend hardware for a specific task, rather than to support existing devices. You may get help on Super User. Mar 16 '17 at 1:26
  • 1
    I don't see this as troubleshooting. The OG is asking what something means on a device. However, you're correct about it violating the purpose of this SE since it's used for recommendation.
    – user5796
    Mar 16 '17 at 1:36
  • Even though I answered your question below, I'm going to vote to migrate this question.
    – user5796
    Mar 16 '17 at 1:36
  • I'm fairly sure the "pc3" is a typo, and it should be "pc4".
    – Mark
    Mar 16 '17 at 20:33

It's points out the type of the RAM :

The "R" is for Registered which is usually used in servers.
The "U" stands for unbuffered non ECC.
The "E" stands for unbuffered ECC (not registred)
The "S" for SO-DIMM, a format of DIMM's used for laptops :)

Those are the ones I know.

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