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Can someone explain to me...

Discussion in 'General Hardware' started by Kantastic, Sep 27, 2009.

  1. Kantastic

    Kantastic

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    How the Nehalem platform and DDR3 memory frequencies are linked to each other? Like, I wouldn't be able to run 2000MHz memory on a 920 at stock clocks right? Is there some sort of set formula or ratio? What is the usual/optimal memory speed for a 920 at 3.8? 4.0?
    Last edited: Sep 27, 2009
  2. kid41212003

    kid41212003

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    The memory controller sit on the same package as the cpu.
    Higher memory frequency requires higher voltage for the controller, at the same time require higher QPI link speed to stay stable.

    3.8GHz = 190baseclock x20 cpu multi or 181x21.

    Memory divider 2:8 (you can change the ratio), result in memory speed of 190/2x8 = 760 (1520MHz), or 181/2x8 = 724

    Same thing with 4GHz, google how to OC an Core i7 for more info on how to stay stable with high memory speed. Different system acts differently...
  3. Kantastic

    Kantastic

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    So if I don't go past 4GHz then buying memory higher than 1600 is pointless?

    (200/2*8=1600)
  4. Mussels

    Mussels Moderprator Staff Member

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    its not as fancy as you think, every platform has always had a memory clock limitation.

    in DDR they went from 266 to 400 as the generations wore on, DDR2 went from 533 to 1066, and so on.

    of course, its good to learn what those stock limitations are, and where the average OC ends up - thats why i went for CL4 800MHz instead of CL5 1066 :)
  5. Assassin48 New Member

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    What i was told is go for better timings then speed
  6. n-ster

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    I thought you could have 2k sticks on stock i7.... the mem divider is changeable...

    I was told ~1600 was optimal... then tweak your timings to the max, then add speed if you can
  7. Mussels

    Mussels Moderprator Staff Member

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    i always suggest for the highest clock rate, at the lowest voltage.

    you can always lower the clocks yourself and aim for better timings, but it gives you the OC headroom on future platforms.

    EG, buying DDR2 667 wasnt needed on early core 2 chips with a 200Mhz FSB, but a few years later when you updated to chips with a stock 333MHz FSB, you suddenly had no headroom to OC.
  8. n-ster

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    but I thought mem speed didn't hinder OC much for i7 except for a bit of stability?
  9. Mussels

    Mussels Moderprator Staff Member

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    i'm not an expert on the 1156/1336 platforms - its just general advice from my years of OCing. if its faster, its future proofing for your next updgrade... whos to say you wont want faster ram if you buy an i9 in a years time?
  10. hat

    hat Maximum Overclocker

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    If you're referring to this... your memory voltage has to be within .5v of your QPI voltage or stuff burns up.
    Crunching for Team TPU
  11. n-ster

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    oh yea thats important info :p But for 1366 there is no ram limitation with the cpu... My advice is to go with the crucials... Great OCability
  12. Binge

    Binge Overclocking Surrealism

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    +1, and to the OP. When overclocking the i7 you worry about the CPU speed. OCing the memory isn't going to buy you much since the bandwidth is already pretty intense.

    Here's how it works:

    1) most frequencies you want to notice will be related to your BCLK.
    2) Memory is the BCLK(Mem-multi). The lowest multi is x6, and the multi increases by incriments of 2.
    3) Memory directly affects your uncore, but your uncore can be overclocked without overclocking your memory. In some cases you do not want to overclock but you will want to increase your uncore in order to achieve a higher BCLK (mostly for going over bclk 200). The product memory frequency multiplied by 2 will be your lowest achievable uncore frequency. Therefore memory at 1333MHz would require you to have 2666MHz total uncore ([133 * 20] where the multiplier of 20 is double the memory multiplier and 133 is the BCLK).
    4) Uncore frequency is a lot like FSB where when you raise the FSB the whole system goes faster. The Uncore with respect to the i7 relates to the speed of the system except for the core and memory. This opens a great many doors for the i7 as it can overclock parts of it's system independantly of one another and greatly simplifies which voltages/settings are changed to increase stability when overclocking those components.

    I hope you learned more than you had to :D
    3dsage and Kantastic say thanks.
  13. n-ster

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    Wow great explanation and clearing stuff up for me ;)

    Binge's knows what he's talking about lol
  14. Binge

    Binge Overclocking Surrealism

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    Si, when it comes to hardware. Sometimes there are dark corners of operating systems that completely throw me for a loop. I'm referring to that thread about the guy who had some sort of MS-config setting which disabled cores... never ever had that experience before.
  15. n-ster

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    Haha your to hard on yourself Binge xD I guess its true, you learn something everyday :)
  16. Kantastic

    Kantastic

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    I'm probably getting myself into way more than I need. Let's hope if I do finally go i7, which I'm fairly certain I will, and soon, I can pick up more knowledge from that point forward. I'll be Googling after I make this post to find an answer, but I feel I should ask here anyway.

    Would mixing 2 different kits of RAM hinder performance provided they're at the same exact speeds? What about 2 different kits running at different speeds? Mainly asking because I might want some low profile memory so that large heatsinks like the TRUE and Megahalems won't be an issue.
  17. Binge

    Binge Overclocking Surrealism

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    Mix & match doesn't work with triple channel as it will not run with unganged memories. Different memories also have different subtimings which would seriously get out of hand unless you had a gigabyte board. The gig motherboards would allow you to change the timings of each slot independantly, but it would not allow you to use different sticks in tri-channel.
    Kantastic says thanks.
  18. n-ster

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    As I said, for the research for the Crucials, the i7 thread has the most info on it in the whole internet!!! :D
  19. Binge

    Binge Overclocking Surrealism

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    EXAMPLE

    s1.s2.s3.s4.s5.s6

    All of the above numbers represent slots... you must first occupy the even slots before you can occupy the odd slots. This is standard on most x58 motherboards. Each set of 3 slots must have memory from the same kit or it will not run in tri-channel. I hope this illustration is clear... you just have to group all from the same kit into one of the two sets of slots, evens or odds. Most motherboards require you to occupy the evens first, so you will have to use the same kit in all even slots.
    Kantastic says thanks.
  20. Binge

    Binge Overclocking Surrealism

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    The i7 thread is no longer a help desk... it has a lot of info, but you have to read a lot of the social parts of that thread too. A ton of photo spam and short responses to hike post counts :p

    Most of the information is burried. I suggest looking for overclocking tips in google or on XS/i4mem/generictechforum by motherboard as understanding the bios is one of the first things covered in those kinds of threads.
  21. Kantastic

    Kantastic

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    I'm not sure I made myself clear enough in that post, let me try and rephrase it.

    Would it be okay to have a config like this?

    OCZ.Kingston.OCZ.Kingston.OCZ.Kingston

    If the answer is a yes, would it hinder performance if they're all running at identical speeds/timings? What about each kit running at different specs?

    And wow I'm picking up a lot of stuff here.. :p
  22. Binge

    Binge Overclocking Surrealism

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    you can run it like that if you want... I stress that OCZ must all be from the same kit as well as Kingston need to be of the same kit. You can't have the OCZ sticks from different OCZ kits etc... You will also have to buy a gigabyte motherboard because there is no other bios that will let you change the timings of each stick independantly. The timings will affect your stability in a major way so this is something to seriously consider. You can run them at the same speeds if you're sure they will independantly run at those speeds with the voltage you decide to give the DRAM as a whole.

    So to recap..
    1) Different kits from different companies = different timings.
    2) As long as sticks can run at the speed you want, no problem.
    3) all sticks are going to run at the same voltage. Make sure that is OK
  23. n-ster

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    I guess that when you know what your looking for, the i7 thread is still a pretty good source... came and always come back to it to help others out ;)

    Is there a reason that you want 2 different sets of RAM?
  24. Kantastic

    Kantastic

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    1 set (taller heatsink'ed HyperX or Trident) and a shorter low profile kit in the future if I decide to upgrade, because with large air coolers it will block the DIMM's on the Gene II. The EVGA X58 micro doesn't have that problem but the Gene II is the superior board... aside from that one little issue.

    This or this for now.
    This OCZ kit if I want to upgrade in the future.
    I'll probably run them both at 1600 if both kits are running on the same board, any higher and the CPU might not be able to handle it.
  25. hat

    hat Maximum Overclocker

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    Binge... I thought BCLK raised the CPU speed? Yet you're saying that it raises the memory speed... does it do both?? I am very confused now
    Crunching for Team TPU

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