1.35 vs. 1.5v RAM Upgrade - mid-2011

Discussion in 'iMac' started by tyz, Sep 21, 2011.

  1. tyz macrumors newbie

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    #1
  2. qap macrumors 6502

    qap

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    For the iMac should be the same, the low voltage RAM banks are for the notebook, I think in the iMac both work with 1.5V if the iMac deliver this voltage to the ram slots.
     
  3. sbbluewater macrumors member

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    I had th esame question so I called Crucial about this and they told me both would work. The 1.35 volt would just run using just a little less power.
     
  4. qap macrumors 6502

    qap

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    Wirelessly posted (Opera/9.80 (iPhone; Opera Mini/6.1.15738/25.872; U; en) Presto/2.5.25 Version/10.54)

    Yes. Some notebooks deliver less V to the RAM so the 1,5V banks could not work or drain the battery but if you put the 1,3V bank in 1,5V slots they shoul have no problem ;)
     
  5. err404 macrumors 68020

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    Isn't the voltage determined by the system board, not the RAM? If so, w/o system support, your 1.35 volt RAM would still get 1.5 volts...
     
  6. tyz thread starter macrumors newbie

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    I also thought the voltage was motherboard dependent -- crucial has it listed as compatible, so I would guess it's supported by the board, but just wanted to be sure.

    If I'm not mistaken the over-clockers tend to prefer the lower voltage cet par as it runs cooler, though I'm not sure if that would matter b/t 1.35 and 1.5v? Is there any performance difference (w/o clock boosting) or meaningful heat difference between the two?

    Or does it really not matter and just go with what's currently in stock (1.5v) so I can get my hands on it??:D
     
  7. err404 macrumors 68020

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    It's more about stability than heat. You can increase RAM stability in an over clocked system by running it a higher voltage (to a certain point). RAM needs to be of a higher quality to run stable at the low voltage. This gives the over clocked more headroom in pushing the voltage.
    The 1.35 volt RAM will work fine in your machine, despite still running at 1.5 volts. If it is the same price, go for it, but I wouldn't pay extra.
     
  8. qap macrumors 6502

    qap

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    Wirelessly posted (Opera/9.80 (iPhone; Opera Mini/6.1.15738/25.872; U; en) Presto/2.5.25 Version/10.54)

    Yep more V is equal to more stabilty in the overclock (inside some limits) because when you rise the clock the banks need more power to run well without errors, not due to less heat (is not the problem).

    Go for the 1,5V :D also because the imac deliver 1,5 to the ram and the 1,5 banks are tested for this V ;)
     
  9. tyz thread starter macrumors newbie

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    Thanks guys -- I think I get it, though I'm a bit confused about which is better and why. While looking into it, I had read a post from a guy building his own system where someone recommended he buy a lower voltage RAM, and it was mentioned overclockers prefer lower voltage chips all else equal.

    Just for my own curiosity -- do I have this straight?:

    - lower voltage chips are considered higher quality RAM and so can be run at a higher voltage than default for an overclocked system (i.e. a 1.35v stick on a 1.5v board is better than a baseline 1.5v chip of otherwise equal specs for this purpose)
    - or is it the other way around -- a higher voltage chip is preferable in an overclocked system, because they can boost the voltage on the board to over 1.5v (I don't think that is what you guys said)?
    - On the 1.5v board of the mid-2011 iMacs, both will be running at 1.5v anyway; the 1.35v stick may be of higher quality, but it's negligible
    - Though they are both the same price, given the 1.5v sticks are in stock, and the 1.35v sticks are not (or maybe they haven't been released yet), you guys wouldn't bother waiting for the 1.35v chips -- won't make any difference in performance, heat build, or stability of the iMac

    other random question for someone who's been out of the loop for a bit on this -- is the trend always toward lower voltage chips for the same specs, same as a smaller processor die is? i.e. the lower voltage version is likely a result of a move to a new manuf. fab?
     

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