Important Info for 2013 iMac 1.35v VS 1.5v RAM Upgrades

Discussion in 'iMac' started by jordanm86, Nov 2, 2013.

  1. jordanm86 macrumors regular

    Oct 21, 2011
    Hey everyone,

    I recently took shipment of my BTO iMac and upgraded the RAM with Kingston HyperX pnp 1600mhz DDR3 RAM 1.5v.

    Everything was fine for around 2 hours and then all of a sudden, my machine shut down and I got a Kernel Panic. Booted back up, same thing shortly after. Three Kernel panics by the end of the first day (on a brand new machine :-S)

    Second day, same thing. Contacted Apple support who said put the Apple RAM back in, test and see if it works. He did say that the documentation would suggest that this RAM is absolutely fine to use (1.5v) and the specifcation and product wiring diagrams do not suggest that it is 1.35v only.

    Switched back to the Apple RAM... no Kernel Panics!

    Sending the RAM back to Amazon tomorrow as i'm guessing one of the sticks must be defective, but interesting that Apple rep confirmed it is ok to use.

    Asked for a refund as I have since heard some Kingston's RAM can be unreliable and don't want to chance it again.

    Any recommendations on brands?
  2. bizzle, Nov 2, 2013
    Last edited: Nov 2, 2013

    bizzle macrumors 6502a

    Jun 29, 2008
    We use 1.5v Kingston (though not HyperX) at work on the new iMacs and it works fine and we've upgraded hundreds. You might just have a bad stick or a bad slot.

    I suggest you run fsck on the drive before using the machine any more to ensure the file system is clean. You can do this in single user mode (boot up holding command+s) and type "/sbin/fsck -fy" without the quotes and after it's done "reboot", or boot into the recovery partition and run Disk Utility with the Repair Disk function. I prefer the single user mode method only because you don't have to rely on the Recovery Partition.
  3. jordanm86 thread starter macrumors regular

    Oct 21, 2011
    Would it be possible/likely that there is a file system issue on brand new machine? I did run an Apple hardware diagnostics test and it stated everything was good but not sure how accurate it would be.
  4. TheyCallMeBT macrumors member

    Jan 9, 2013
    I will only buy from Crucial. I had an issue with my old MacBook Pro, that I think may have been related to the memory that I upgraded it with. But I used the search tool on Crucial's website to get the memory upgrades for my iMac, and it has worked very well.
  5. bizzle macrumors 6502a

    Jun 29, 2008
    I am talking about now that you've had a bunch of kernel panics, the file system could be slightly banged up.
  6. juay macrumors newbie

    Nov 5, 2013
    jordanm86, don't use 1.5v RAM, regardless of brands. You probably will have kernel panic error after few hours of intensive usage. I installed 32GB, 2 different batches of 1.5v, Kingston KVR16S11/8 & KTA-MB1600/8G (Equivalent Apple). Both freeze after few hours. Yesterday I tested on 32GB 1.35v Crucial RAM no issue. Last weekend, I was running 16GB 1.35v Apple RAM + Crucial RAM without any issue too. I also remember that I used 32GB Kingston KVR16LS11/8 on BTO iMac Late 2013 without any issue few weeks ago. I believe only “L” 1.35v RAM will have no issue with iMac Late 2013.

    Don't need to use command+s to test. Best test is still 2-3hrs intensive use with graphics applications. When using 1.5v RAM, I occasionally get black out, white screen, kernel panics & sometimes applications quit for no reason but Press "D"-useless quick Apple hardware test passed. With 1.35v, I have no issue.
  7. AL2TEACH macrumors 6502

    Feb 17, 2007
    Denver, CO.
    I got my ram from OWC because I read it's the same brand as Apple's. costs a little more but problem and stress free.

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