So my ThinkPad has a free slot and I wanted to buy another 4GB stick for dual channel. Knowing that timings matter somewhat more in notebooks I checked cpu-z and it said that timings were 11-11-11 (CL-tRCD-tRP). So I went ahead and got a DDR3-1600 stick with those timings. Haven't put it in yet though.

What confuses me is the nomenclature: If you look up: https://en.wikipedia.org/wiki/DDR3 a DDR3-1600 module with timings 11-11-11 is called DDR3-1600K. Now I don't remember what the Lenovo page said about RAM used but it sure doesn't have a "K" at the end. Then the RAM I bougth was called "CL11". So that refers to CAS latency right? Wikipedia has "CL" as part of the timings and a separate number for CAS latency which is 13 3/4 in case of 11-11-11. What does "CL11" refer to?

Is there something else besides I/O bus clock and timings I have to keep in mind? Does voltage matter? What about Cycle Time and Bank Cycle Time?


Nobody but JEDEC and the chip manufacturers use the suffix letters. Marketing names and user manuals always use the plain "technology-speed" nomenclature (eg "DDR3-1600").

The Wikipedia table measures CAS latency two different ways: "11" is the latency in bus cycles, while "13 3/4" is the latency in nanoseconds.

For the most part, you don't need to worry about anything besides the technology (eg. DDR3) and the speed (eg. 1600). Unless you're buying premium parts for overclocking, voltage isn't an issue. Your computer's mainboard can usually adapt to a wide range of access timings, so the exact timing you pick is mostly a matter of slight variations in performance.

  • But I thought that if you add another module to your notebook for dual channel timings do matter? – H3R3T1K Jun 27 '15 at 8:52
  • Yes and no. They matter in the sense that the mainboard will slow things down to match the speed of the slowest module, but they don't matter in the sense that you'll get the benefits of dual-channel whether they match or not. – Mark Jun 27 '15 at 9:04
  • I heard mismatched timings can cause havok in a notebook. That's not true anymore? – H3R3T1K Jun 27 '15 at 11:09
  • That's only true if the notebook BIOS is faulty, or it pre-dates memory plug-and-play (late 1990s or thereabouts). – Mark Jun 27 '15 at 18:03

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