After replacing HDD cable, low disk speeds

Discussion in 'MacBook Pro' started by jamesjingyi, Jan 17, 2015.

  1. jamesjingyi macrumors 6502a

    jamesjingyi

    Joined:
    Dec 20, 2011
    Location:
    UK
    #1
    Hi all,

    After replacing my hard drive cable, my MacBook Pro has been getting disk read speeds of about 120mb/s. Installed is a Samsung 840 Pro SSD. However it seems to get about 440mb/s write. Is this a fault? I am pretty sure before I replaced the cable I was getting a lot higher speeds. I am wondering whether it is a fault with the cable or whether Blackmagic Disk Speed Test is just giving me bad results. Is there another way to check?

    Thanks

    James
     
  2. Brian Y macrumors 68040

    Joined:
    Oct 21, 2012
    #2
    First of all, why did you replace the cable? The original issue might be key.

    It could be the disk dying - what kind of speeds do you get if you just copy a large file in Finder?
     
  3. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #3
    What happens when you put the older cable back?
     
  4. jamesjingyi thread starter macrumors 6502a

    jamesjingyi

    Joined:
    Dec 20, 2011
    Location:
    UK
    #4
    I replaced it because it did not show up in the computer at all and would not boot (? Folder).

    After replacing the thing worked again

    The drive is fine as everything works well and I can boot from other computers using an external hard drive caddy

    ----------

    Nothing, the old cable is completely dead
     
  5. KUguardgrl13 macrumors 68020

    KUguardgrl13

    Joined:
    May 16, 2013
    Location:
    Kansas, USA
    #5
    I have no idea if this is the case or if it's even possible, but maybe you installed a SATA II cable instead of a SATA III? I know that older Macs that are limited to SATA II can't get the speeds that most SSDs specify.
     
  6. AlexMaximus macrumors 6502

    AlexMaximus

    Joined:
    Aug 15, 2006
    Location:
    A400M Base
    #6
    shield it..

    The only thing that comes to mind it to shield the cable.
    The original is a very flat non shielded cable. OWC once offered a shielding kit to wrap the cable for faster speeds and less errors for the MBP 17'
    According to IEEE specs, a shielded cable can transmit more data and chances of error is significant less. Thats what I did. Its experimental, but it "felt faster" since then.
    The kit is not available any more, however check youtube for shielding cables.

    :apple:
     
  7. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #7
    Pick up another cable then, but I wonder if its some other hardware failure.
     
  8. jamesjingyi thread starter macrumors 6502a

    jamesjingyi

    Joined:
    Dec 20, 2011
    Location:
    UK
    #8
    OK, thanks for your help everyone, I'm gonna try and get this fixed asap!
     

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