What do all the numbers mean?

This ASRock Z77 Extreme4 Motherboard is the motherboard I've selected for my new build.


I've also selected a Cooler Master Hyper 212 EVO aftermarket cooler for my CPU. It was suggested that I look at getting some low profile memory. OK I understand low profile basically means smaller so it will fit. What I don't completely understand is DDR3 1600/1866 PC3 12800/PC314900 etc.

Add to that the fact that the motherboard I've selected has (OC) next to DDR3 1866 it leads me to believe I either need to overclock the memory or overclock the motherboard in order to get it to work with the 1866 RAM.

For Top Gear fans I don't need the James May explination, but what I would like to know is if the larger numbers mean better performance and if the price is almost the same (i've found DDR3 1866 chip sets $1 more expensive than the DDR3 1600 sets from the same series) doesn't it make sense to spend an extra buck? I've been doing research and on more than one occasion DDR3 1600 has been suggested to me. The thing that really gets me about that is the fact that my 2 year old machine has DDR3 1600 RAM in it.

The other thing I am curious about is dual channel. Is the motherboard I've selected going to support dual channel? Is dual channel ram something different than what I've been looking at? I've read enough to know that there is a lot I don't know, but I know enough to know this stuff is important when picking pieces.

The system is going to be used for online sim racing.
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More about what numbers mean
  1. 1) There is VERY little performance diff between DDR3-1333 and DDR3-1866. Normally the Difference only shows up in benchmarks and NOT in Day-to-day usage. There are a few apps that can benifit from increased bandwith (Speed). Same same for CL7 -> CL9 - Games generally are NOT one to benifit from higher ram speed. Also as Ram speed increase often the CL ratings increase which will temper any performance gain based on speed. (ie CL7 faster than CL9, but again only noticable in benchmarks

    2) Daul channel. can effect performance some. Not a problem, just buy your RAM in pairs (Kit) and it will run in Daul channel. Daul channel means that memory request are completed in parallel thus theporically doubling the performance over single channel operation.

    3) You did not specify which CPU.
    .. Any Ram that is above the spec is classed as Overclocked Ram. What this means if you stick 1600 in a SB system it will default to 1333 and YOU have to go into Bios and manualy set to 1600 (ie select XMP, profile 1). IB defaults to 1600, so same-same if you stick 1866 Ram in. That Said I'm running DDR3-1600, CL7 @ 1.600 V in my i5-2500k system (NOTE make voltage for Ram for SB is 1.575V, probly the same for IB.
    .. If SB CPU, play it safe and get DDR3-1333. Reason is that, unless you buy he Intel OC warrenty (ie $25 for i5-2500K) any ram run above 1333 void intel CPU warrantee - ONLY a problem if CPU dies, Intel MAY disapprove RMA. Specc for SB is 1333
    .. If IB Cpu. The spec was raised to 1600, so MOST likely same-same if Ram Higher than 1600. Hope this helps and answers Most of your questions.


    DDR means that the ram processes a request on both the leading and lagging pulse (single DR Ram only proceessed request on leading edge, so DDR should be twice as fast.
    DDR2 is meant to operate DDR in daul channel mode, hense twice as fast as Single channel Mode.
    DDR3 really places 3 ram modules in parallel, HOWEVER most MB only allow for Dual channel Mode, so Most DDR3 ram is operated as DDR2. Example DDR3-1600. Input clock freq is increased to 400 (ie for IB 100 Mhz (bclock) x 4 = 400 Mhz). The The "2" = 2 x 400 Mhz = 800 Mhz. and if in daul channel again this is multiplied by 2 so 800 x 2 = 1600.
    The other Numbers. PC12000. The PC312000 is IF operated in triple channel Mode effective speedand the last Number (ie PC314900) is How Much faster (Theorically) it is compared to the Orginal memory speed back in the days of BC - LOL
  2. Wow Thanks. That is some really useful information. CPU is an i5 3570K which is an ivy bridge chip. That leads me to believe I should get some DDR3 1600 low profile performance RAM. Now to find some.

    I'm doubting this matters much, but I'm guessing there is no such thing as low profile when it relates to a performance series. I'm wondering based on the timings if the performance series is simply a bunch of plastic bits to make the stuff look awesome rather than actually perform any better than a regular module.
  3. Generally Low profile is required only if a problem with the HSF that you install and then it also depends on how close the 1st ram slot is to being underneath the HSF. Hight is general based on the heat sink that is installed on ther ram.

    I then to faver the Ripjaw Line.
    Like this What I'm using in two systems - Except Mine ins CL7 instead of CL8 and V reqiuired on mine is 1.60 V vs 1.5 V:
    If concerned about hight then:
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