4MEM hardware test error/kernel panic

Discussion in 'iMac' started by sharky867, Jun 24, 2010.

  1. sharky867 macrumors newbie

    Jan 28, 2009
    My imac has started to crash recently with "You need to restart your computer. Hold the Power button for several seconds or press the Restart button." Known as the grey screen/black screen curtain. To troubleshoot problem I ran the Apple Hardware Test and received error message 4MEM/1/40000000:0xb951c818. I understand it is a memory/ram problem.

    My setup is 24" imac 2.93ghz Intel Duo CPU
    4GB memory
    OS X 10.6.4

    Anyway to fix this problem, my warranty is out. I would appreciate any suggestions to this problem.

    Thank you.
  2. aki macrumors 6502a

    Mar 2, 2004
    I had the same problem a while back (before my logic board died :( ). You are lucky, your problem is simple.

    One of your ram sticks has dieded. I don't know if you have one 4GB or 2x2GB but if the former you need to buy a new one and if the latter you need to test which is dead and then buy a new one.

    It's no great crisis, just order a new RAM stick of the correct type (the apple website among others can tell you exactly what type of RAM you need; or you can look at the sticker on your old RAM). Place your imac face down on a clean table. Make sure you aren't charged up on static electricity. Use a philipshead screw-driver to open the small panel at the base of the iMac display and pop out the cover. Inside you will see two RAM bays. Unfold the black plastic strip and gently but firmly pull at the strip, which will tug the RAM stick out. Remove the stick, insert the fresh one, same orientation and everything. They are usually a bit stiff, just press it in, they aren't that fragile so you can apply some force, just use common sense. Once the fresh RAM is fully in, curl back the plastic strip, and replace the cover.

    Then you may as well run the memory test again, just to be sure you replaced the right one and everything is peachy.

    There are better descriptions of this process along with photos on various sites, google around if my rough description doesn't fill you with confidence.

    But don't stress, dead RAM is no great crisis, it happens. Good luck!
  3. blowfly65 macrumors newbie

    Sep 27, 2010
    Leicester UK
    Apple hardware test

    I had a similar problem today - screen goes grey, "You need to restart your computer" etc.

    Using Disk Utilities on OSdisk 1, I got error message "Incorrect block count for file pcsd.pub (It should be 16 instead of 17)". I repaired this successfully but still got same restart message so carried out hardware test. Result: "Alert! Apple Hardware Test has detected an error 4MEM/4/40000000: 26c84010". I then carried out an extended test and in the section "Testing, main logic board" got another Alert 4MEM/1/4000000: 234000.

    Does this mean that the mother board has died? Machine is out of warranty so it sounds serious/expensive.

    I bought an Apple Mac partly because they used to go on for ever but this one is only 18 months old. Are these hardware problems now common?
  4. blowfly65 macrumors newbie

    Sep 27, 2010
    Leicester UK
    4MEM hardware test error/kernel panic

    OK - problem solved, I think.

    1. I used the free AppleStore helpline and got some very helpful advice, testing as far as was possible over the telephone and making an appointment for me at my local AppleStore.

    2. I removed the 2 RAM chips as suggested (very easy) and tried cleaning the contacts with an eraser but this didn't work.

    3. The free check at Apple Store identified which of the two components was faulty. The iMac now boots up and runs with the faulty one removed, albeit more slowly. The files stored on the hard drive are of course unaffected, but this has reminded me of the need to back up more frequently just in case.

    4. AppleStore would have replaced the faulty 1GB chip at a cost of £60 + around £40 labour! I have ordered an identical replacement for £13 from an eBay dealer I found on the internet. It will take me 5-10 minutes to fit. AppleStore charges are high, though the help I received from Apple staff was first rate and free.

    5. I have not increased RAM but could have done so by replacing both chips identically with larger capacity (eg 2 x 2GB) for about £50. The guy at AppleStore advised me not to increase memory asymmetrically on this dual coremachine and I decided that I did not need to spend an additional £37 increase from 2GB to 4GB for what I use the machine for.

    6. So I've learned quite a lot from this and it hasn't cost me too much (apart from time).

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