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Which is better: 9, 10, or 11 CAS RAM

Hello,

Im looking to upgrade the ram in my computer, and was wondering if I should go with the Corsair Vengeance DDR3-1600 2x8 16GB Ram with 9, 10, or 11 CAS... Basically do you want low CAS, or high CAS?

Also, which type of corsair RAM would be best for video editing, and gaming? Corsair Vengeance, Corsair Dominator, Etc...
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More about cas ram
  1. Best answer
    Low cas is better.

    In many cases, if the board and cpu support it higher speeds can help.

    Outside of benchmarking, many users will not notice the difference.
  2. Lower CAS is faster. CAS is short for CAS latency, that meaning how long the delay is between when the RAM is queried and how soon it responds (measured in clock cycles)
  3. I'm looking at CAS9 vs CAS11 memory for a Dell Latitude E6440 i7-4610, and the memory vendor said "CL11 model may work better for the Dell computer. CL9 is generally not supported." Why would a system not support a lower latency?
  4. Normally it would be a chipset limitation(not likely since the memory controller is in the cpu), but I would check what the stock memory is running at.

    A program called cpuz can show you this information.
    http://www.cpuid.com/softwares/cpu-z.html

    Check the memory tab.
  5. Thanks; looks like it's 11 now:

    Northbridge Intel Haswell rev. 06
    Southbridge Intel QM87 rev. C1
    Memory Type DDR3
    Memory Size 8 GBytes
    Channels Dual
    Memory Frequency 799.0 MHz (1:6)
    CAS# latency (CL) 11.0
    RAS# to CAS# delay (tRCD) 11
    RAS# Precharge (tRP) 11
    Cycle Time (tRAS) 28
    Row Refresh Cycle Time (tRFC) 208

    But the question remains: Why would a lower-latency module cause problems? Does the chipset require that extra 2 cycles for something?
  6. In some cases it simply can not operate that way.

    It is pretty rare to be honest. I had an old laptop that would not work with faster memory, but would still try to run at that speed(this caused the system to blue screen from time to time.).

    I find it hard to believe that CL9 memory would cause issues(just ensure you are using memory that operates on 1.5 volts), but if you are worried and want to play it safe, getting CL11 will be an option.

    If you are keeping the old and new memory, the system will auto default to CL11 since it will use the slowest stick as the speed for all.
  7. All I could think of was a timing situation where the memory controller would assume it had a couple cycles to play with while waiting for the memory to respond or the value to stabilize, and CL9 came back too quick for that strategy to work, but that's a real stretch, to say nothing of poor design. CPU-Z worked fine, but it has to be run as administrator, not mentioned in their basic documentation. I run all my machines in non-admin mode as a security hedge. Finally, this PC runs memory at 1.35V; The memory vendor was very helpful with research & part numbers, so I've got the "correct" parts on order now. Thanks for your help.
  8. If the board only supplies 1.35v ddr3 it should be DDR3L

    In that case make sure your memory will do the boards set speed at 1.35 since 1.5 is the standard.

    Very good to hear the memory vendor is being so helpful.

    I run some of my DDR3 @ 1.35 volts(and it was rated for 1.65, but I have clocked lower anyway).
  9. How do you check your CPU/motherboard for the speeds they can handle? As I want the optimal!
  10. Also CAS over clock speed?
  11. Check the manual for supported memory.

    In some systems faster memory clocks may require the cpu to be overclocked(you should keep an eye out for this if you do not want to overclock). This happens when the board does not have a memory multiplier to work with the faster speed so the cpu base or fsb is increased as well.

    Memory speed vs latency tends to depend on your program or game. Getting a faster speed as long as the latency does not go up too much should improve performance(how much depends on the software in use.).
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