MacBook Pro RAM - 1.5V vs 1.35V

Discussion in 'MacBook Pro' started by Baloney1011, Mar 28, 2012.

  1. Baloney1011 macrumors member

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    #1
  2. shardey, Mar 28, 2012
    Last edited: Mar 28, 2012

    shardey macrumors 6502a

    shardey

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    #2
    More than likely, you won't see any difference in battery. What laptop are you using? If it came down to it, I would go with the lower voltage, unless there has been reported problems with the model of MBP you have and other users experiences.
     
  3. Ccrew macrumors 68020

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    Feb 28, 2011
    #3
    I always love how this claim flies around here.

    The voltage is the voltage at which the memory meets it's advertised specification. Since Apple computers don't have a Bios, or (easily) modifiable EFI, you can't set the voltage. It is what it is. The MacBook Air is the only low voltage memoried computer in the Apple product line. Some will argue that if you send 1.5v (default) to a 1.35v DIMM it'll overclock it, but at the same time it can also introduce instability.

    Buy what's cheaper and don't pay attention to voltage specs. Timing and CAS Latency is what will make or break it.
     
  4. shardey macrumors 6502a

    shardey

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    #4
    Maybe if we could over clock the ram in MBP's then I would understand the lower voltage, but..... You can't, as far as I know
     
  5. Baloney1011 thread starter macrumors member

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    #5
    They're both the same price, though! So, do I just sort of pick one randomly and hope for the best or what? How are people supposed to decide which one to take?
     
  6. salacious macrumors 6502a

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    #6
    i bought the 1.5v, no problems here 8gb running a dream..
     
  7. Baloney1011 thread starter macrumors member

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    #7
    And how did you decide which one to buy?
     
  8. salacious macrumors 6502a

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    #8
    well basically the 1.5v from what i understand was standard, as i dont know much about the technical side of ram voltage, i decided to go with the general consensus its .15 of a voltage more than the 1.35v i doubt theres that much of a difference, so i thought should i wait a couple of days or just get the bloody thing..

    needless to say i made a good choice..

    i got a 13" mbp 2011 early i5

    rendering times have been cut down alot

    if that answers anything
     
  9. Ccrew macrumors 68020

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    #9
    Standard is 1.5v, just buy that. Understand that the 1.35 they're listing is simply listed as "compatible" meaning they'll support it, not that it's a perfect match.


    Reality is that either will probably run fine, but if given the choice best to stick with the default for the machine. Were this a PC with a bios that could be tweaked my answer may be different.
     
  10. Baloney1011, Mar 29, 2012
    Last edited: Mar 29, 2012

    Baloney1011 thread starter macrumors member

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    #10
    Okay, thanks, I ordered 1.5 volt. :)
     
  11. bill-p macrumors 68000

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    Jul 23, 2011
    #11
    I believe 1.35v would just work at 1.5v.

    I had a 1.35v 8GB pair in my MBP prior to getting a 1.5v 16GB pair. No difference in battery life, but big difference to my productivity (RAM capacity related).

    Now the 1.35v 8GB pair is put in an older Vaio laptop (runs Core 2 Duo). No major issue at all.
     
  12. cosmicjoke macrumors 6502

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    Portland, OR
    #12
    I own 2 Late '11 Macbook Pro's (well, I gave my first one to my lady when her laptop died) and both have crucial ddr-3 1333mhz ram, my lady's has 1.5v and mine is running 1.35v... both run flawlessly, no discernible difference between either.... it's pretty impossible to measure an alleged 8 mins of battery time so... wouldn't fret about it whatever you get...
     
  13. Dysfeathered macrumors newbie

    Dysfeathered

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    #13
    CCREW You are only partially correct. Voltage of the RAM modules installed to a motherboard are just as important as CAS and clock speed. 1.5v is the default standard of RAM across motherboards. 1.35v is supposed to provide a performance boost but if and only if the motherboard supports it. In my experience with boards across apple and Non-apple. If modules rated at 1.35v are installed into a board that only supports 1.5v--i.e. the intel dx79sr and like models-- then your system may not properly boot. Since Macs tend not to allow access to any kind of bios setup menu its safer to assume that 1.5v--the default standard for RAM--will work. To order a pair of sodimms rated at 1.35v is a gamble. Though It is theoretically possible that apple has written things to automatically detect which voltage is required and distribute that voltage accordingly, there is no way for you as the end user to control and verify which voltage is set. it is also just as possible that they didnt write such a feature into the efi or not into every A12~~ model that features removeable Sodimms. Thus you run the risk of having to return those 1.35v sticks if purchased. Also since you cannot control the set voltage via a efi setup menu you also run the risk of slowly sizzling your 1.35v modules due to the fact that they might receive a higher voltage than required thus unnecessarily degrading the life of your RAM. that being said I would go with the 1.5v modules over the ones at 1.35 volts.

    Also My appoligies CCree for possibly coming off as rude. That was not my intent. Thr original question posted was by a user new to computer hardware and it would be unfortunate if he had to learn the difference of 1.35v vs 1.5v the hard way as I've had to with that Intel DX79SR I mentioned earlier.
     
  14. leman macrumors G3

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    Oct 14, 2008
    #14
    The 2011 MBP was shipped using 1.5V PC3-10600 DDR, so that is the RAM I would get.
     
  15. JTToft macrumors 68040

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    Aarhus, Denmark
    #15
    - I'd say this is wrong. As part of the JEDEC memory standard, 1.35v modules must be able to run at 1.5v.
    Thus, 1.35v modules are compatible in machines that require 1.5v.
     

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