iMac Haswell + CL9 RAM @ 1.35V

Discussion in 'iMac' started by IA64, Nov 8, 2013.

  1. IA64, Nov 8, 2013
    Last edited: Nov 29, 2013

    IA64 macrumors 6502

    Joined:
    Nov 8, 2013
    #1
    So I ordered an iMac late 2013 maxed out ( 1TB Flash, core i7 and 780M ) except for RAM.

    And now that I'm waiting for delivery, I spent 4 nights in row trying to check for RAM compatibily but I literally couldn't find anyone trying the CL9 @ 1.35V.

    I've ordered the KHX16LS9P1K2/16 x2 ( 32 GB) for $406( Tax included ) :

    Kingston Technology HyperX Lovo16 GB Kit (2x8 GB) 1600MHz DDR3 PC3-12800 Non-ECC CL9 SODIMM 1.35V.

    Technical details :

    PnP JEDEC TIMING PARAMETERS:
    • DDR3-1600 CL9-9-9 @1.35V or 1.5V
    • DDR3-1333 CL8-8-8 @1.35V or 1.5V
    • DDR3-1066 CL6-6-6 @1.35V or 1.5V

    Programmable CAS Latency: 11, 10, 9, 8, 7, 6

    Row Cycle Time (tRCmin) 48.125ns (min.)
    Refresh to Active/Refresh 260ns (min.)
    Command Time (tRFCmin)
    Row Active Time (tRASmin) 33.75ns (min.)

    ================================================

    Ironically, Apple doesn't mention anything about voltage compatibility nor CL on their website.

    Although CL9 will not be noticeably faster than CL11 for the average joe, but I run intensive, resource demanding applications ( 3 hours for each task minimum with file output > 10 GB ) So saving few minutes is welcomed.


    From the informations I gathered I could confirm that :

    - 2012 Macs can take CL9 @ 1600MHZ but @1.5V
    - 2013 Haswell models are not stable with DIMMs @1.5V - overheat/crash
    - 2013 Haswell models run smoothly @ 1.35v but with CL11 and some CL10
    - 2013 Haswell models can run 1866MHz RAM @ 1.35V with no issue - CL11 / CL10


    There has been reports related to kernel panic and system crash with CL9 @1.5V with Haswell CPUs however, none mentioned if it was due to the higher volatege or the lower latency.

    The fastest RAM stick I could find was the HyperX Lovo KHX16LS9P1K2/16.

    I find no reason why this should not work out of the box but I still have doubts and need some opinions here. I still have till Monday to cancel my order.

    Thanks.
     
  2. Johnf1285 macrumors 6502a

    Johnf1285

    Joined:
    Dec 25, 2010
    Location:
    New Jersey
    #2
    I've had success on my 2013 27" i7 and G.Skill RipJaws running at CL 9 and timings of 9-9-9-28 at 1.35v

    http://www.newegg.com/Product/Product.aspx?Item=N82E16820231705

    Edit - now that I think about it I should probably boot into windows and confirm the voltage, timings, etc.

    Will do later tonight when I get in from work.
     
  3. Jaguarxl macrumors member

    Jaguarxl

    Joined:
    Nov 29, 2012
    Location:
    Brazil
    #3
    Like you, I ordered latest iMac 27". But, I maxed out CPU and Gpu and upgraded to Fusion Drive 1Tb and left ram 8gb.

    I'm ordering after doing some research trying to find a good memory upgrade. I found one from g.skill and I'm going to order a pair of 16gb (2x8). Not a cheap memory, but I believe it delivers! It's $20 cheaper at newegg. Sadly I can't buy one from them.... :(

    16GB G.Skill Ripjaws DDR3 1600MHz SO-DIMM laptop memory dual channel kit (2x 8GB) CL9 - 9-9-9-28 / 1.35V
    http://amzn.com/B00EOTYZOA

    ----------

    Nice!! I would like to hear from you how this memory goes!
     
  4. alksion macrumors 68000

    alksion

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    Sep 10, 2010
    Location:
    Los Angeles County
    #4
    You can confirm that these are running at the 1866MHz and stable? If so, why didn't Apple just give the higher end iMacs this clock speed from the get go?
     
  5. Johnf1285 macrumors 6502a

    Johnf1285

    Joined:
    Dec 25, 2010
    Location:
    New Jersey
    #5
    They run at 1600mhz out of the box. I haven't attempted to up it beyond that and am unsure how to since there isn't any sort of Bios to access (not sure if this is still true, but if I recall AMD systems really got the most out of higher clocked ram).
     
  6. IA64 thread starter macrumors 6502

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    Nov 8, 2013
    #6
    Can you please check it with CPUz under bootcamp ? I would like to know if the iMac is running the RAMs at CL9 instead of CL11.

    Looks like the G.skill is faster than the Kingstone Lovo with tRASmin = 28
     
  7. IA64 thread starter macrumors 6502

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    Nov 8, 2013
    #7
    Looks like a lot of people got the 1866MHz....

    http://browser.primatelabs.com/geekbench3/148873

    etc...

    Score boosted +10%
     
  8. alksion macrumors 68000

    alksion

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    Los Angeles County
    #8
  9. IA64 thread starter macrumors 6502

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    Nov 8, 2013
    #9
    I am still waiting for a confirmation of readings under bootcamp. But I guess I'll change my mind and go for the 1866MHz.
     
  10. Johnf1285 macrumors 6502a

    Johnf1285

    Joined:
    Dec 25, 2010
    Location:
    New Jersey
    #10
    So sorry just realized I do not have a copy of windows currently installed on this machine (I had to swap my iMac with Apple due to screen issues - the original had an installation). Will have some news hopefully tonight! Apologies on the delay!
     
  11. IA64 thread starter macrumors 6502

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    Nov 8, 2013
    #11
    Bumpy bump
     
  12. alksion macrumors 68000

    alksion

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    Sep 10, 2010
    Location:
    Los Angeles County
    #12
    I'll second that bump. Curious to see any new info.

    Anyone want to buy me 32GB of RAM? Ill post the info ;)
     
  13. omnisphere macrumors member

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    Mar 22, 2011
    #13
    Apple state 1600 MHz DDR3 SDRAM and Intel DDR3-1333/1600 so I would not go for 1866MHz.

    ;)
     
  14. Jaguarxl macrumors member

    Jaguarxl

    Joined:
    Nov 29, 2012
    Location:
    Brazil
    #14
    I just place an order for these babies!!
    Just waiting apple to ship my imac so I can try these memories.

    16GB G.Skill Ripjaws DDR3 1866MHz SO-DIMM laptop memory dual channel kit (2x 8GB) CL10. 10-10-10-32
    http://amzn.com/B00EOTVZV6
     
  15. cpc6128 macrumors newbie

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    Oct 24, 2013
    #15
    Can you let us know if 1866 ram is stable?

    And has anyone got 32gb of OWC ram in their Haswell iMac with no issues whatsoever?
     
  16. alksion macrumors 68000

    alksion

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    #16
    Apple has always been known to suggest what they've tested not what's possible.
     
  17. Jaguarxl macrumors member

    Jaguarxl

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    #17
    Yup! Soon I can get my hands on it I´ll let you guys know what happened!:)
     
  18. cpc6128 macrumors newbie

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    Oct 24, 2013
    #18
    Guys, would it be safe to continue to use 2x8gb (16gb) Corsair Vengeance 1.5v in my iMac? It is not causing any Kernal Panics at all. (only when it's 32gb)
     
  19. Johnf1285 macrumors 6502a

    Johnf1285

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    Dec 25, 2010
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    New Jersey
    #19
    I can't find my thumb drive with Windows 8 on it. I'm having difficulties finding a direct ISO download from Microsoft for 8 (not 8.1 and not a .exe downloading program). I have a valid Win8 key.. Ah what to do...
     
  20. IA64 thread starter macrumors 6502

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    Nov 8, 2013
    #20
    Download Windows 7 ? http://technetwindows.blogspot.com/2012/10/windows-7-iso-download-free.html

    Cheers.

    ----------

    I'd always go for the 1.35V with the Haswell but again it' just me.
     
  21. Jaguarxl macrumors member

    Jaguarxl

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    #21
  22. GXPvince macrumors regular

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    May 12, 2008
    #22
    Jag thanks for keeping up with that and letting us know the results. Good information to know when I get my new iMac.
     
  23. mossy macrumors regular

    mossy

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    Sep 11, 2013
    Location:
    Ireland
    #23
    I have RAM (Crucial) from late 2012 iMac installed.
    It works fine here.
     
  24. Jaguarxl macrumors member

    Jaguarxl

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    Nov 29, 2012
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    Brazil
    #24
    You're welcome! I'm looking to test again with overclocked GPU, soon I can find some time to do that!
    About memory, I noticed a lot of people complaining about Kernel Panic, random reboots, problems while trying to install new memories with common brands like crucial, kingston and corsair. The ones I read about using G.Skill ones didn't had any problems at all. I'm not saying the other brands are bad, but all the problems related to memories I didn't see anyone complaining about G.Skill.
     
  25. cpc6128 macrumors newbie

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    Oct 24, 2013
    #25
    The problem occurs when 32gb is installed. I had no problems with only 2x8gb 1.5v corsair vengeance - only when i all 4 sticks (32gb) i experienced issues.

    I have got the owc ram (32gb) and no issues so far.
     

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