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I have an ASUS P9X79 motherboard which supports "DDR3 2400(O.C.)/2133(O.C.)/1866/1600/1333/1066 MHz."

http://usa.asus.com/Motherboards/Intel_Socket_2011/P9X79/#specifications

My Intel 3820 only supports "DDR3-1066/1333/1600."

http://www.intel.com/content/www/us/en/processor-comparison/processor-specifications.html?proc=63698

I purchased "G.SKILL Trident X Series 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 2400 (PC3 19200) Desktop Memory Model F3-2400C10D-16GTX."

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231589

Based on the statement about the Intel 3820 processor, will my computer still operate despite having this G.SKILL RAM with a higher frequency installed? Will it simply step the frequency of the RAM down to 1600?

Thank you all.

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  • Yes it will work, but it will be downclocked, why did you purchase faster memory then your motherboard supports?
    – Ramhound
    Oct 25, 2012 at 20:34
  • If I am not mistaken, my motherboard does support it.
    – user76275
    Oct 25, 2012 at 20:42
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    @Ramhound: When your memory is faster than the CPU or motherboard can support, you get the lower clock speed, but you also get lower latencies. So if the price isn't significantly higher, you should definitely purchase the faster memory. (Slower memory is frequently just faster memory that failed to qualify at the higher speed. So you'll have less safety room as well.)
    – David Schwartz
    Oct 25, 2012 at 21:09

4 Answers 4

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Yes, it will work.

It will work because the higher speed RAM does not have a higher speed. It has a higher maximum speed. The difference in words might be small, but is essential.

I think it is clearer if you think of it in these terms: Can I still use a car with a maximum speed of 100kmph on a 50kmph road?

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Most likely it will. However the memory will be downclocked so that it will operate only as fast as the maximum speed of the motherboard allows.

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  • In this instance, the motherboard supports 2400 MHz which is the same frequency of the RAM itself. So, did you intend to say "that it will operate only as fast as the maximum speed of the processor allows"?
    – user76275
    Oct 25, 2012 at 20:35
  • @H3br3wHamm3r81: It's academic because it's the motherboard that enforces the CPU's speed limits.
    – David Schwartz
    Oct 25, 2012 at 21:11
  • I'm not wishing to argue, but I'd like to further understand. Why then does Intel's website list frequencies for its processor if it is the motherboard that "enforces the CPU's speed limits"? If my mobo supports 2400 MHz, but my CPU does not (according to the website), will I be able to achieve 2400 MHz from the RAM (in theory)?
    – user76275
    Oct 25, 2012 at 21:19
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    There are several parts here that need to be addressed. 1) In the past the motherboard determine the base clock. That was long ago. Today clock generation is done in the CPU itself. 2) board, CPU and RAM do not have to run at the same frequency. E.g. your part of your motherboard may run at 100Mhz, the CPU at 24x100Mhz and your memory at 400Mhz. All these components communicate with each other. If the copper lines on the motherboard are for some reason not able to transfer signals at 400Mhz then you can use RAM at speeds up to 400Mhz even if the RAM on its own could run faster.
    – Hennes
    Oct 25, 2012 at 21:52
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    @H3br3wHamm3r81: The motherboard checks what CPU is installed, checks what RAM is installed, checks the BIOS settings, and then configures the memory controller (in this case, physically part of the CPU) for the appropriate clock speed and latency. If Intel says a CPU only supports 2400MHz RAM, then unless configured otherwise, the motherboard will not configure the memory controller for a speed higher than that because it's not guaranteed to work.
    – David Schwartz
    Oct 26, 2012 at 18:32
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@kobaltz i agree with you, and that means that you are limited by your most limited clock speed among all of your CPU, Mobo and RAM. The 3 need to synchronise with each other. However, the motherboard is more crucial, because it controls how the multiplier operates to configure the synchronisation. You have to work within Maximum Bus speeds, and a range of multipliers with which the motherboard can be configured. Many combinations of CPU and RAM simply won't work with a particular model of motherboard, though traditionally, same gen tech synchronises with same gen tech.

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Unfortunately it doesn't always down-clock the ram. Sometimes the laptop simply doesn't support certain memory.

I agreed with Hennes's and other answers on stack exchange so I got a 1600Mhz card and it didn't work because my laptop only supports 1066Mhz. Typically you will get a kernel panic if you have issues with your memory: http://en.community.dell.com/support-forums/laptop/f/3518/t/19595153

In conclusion just be careful and do some research on your specific hardware because not all rams are supported...

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