MacBook Pro loses access to 1 memory slot upon shutdown or reboot in OS X 10.8.1

This didn't happen to me until I upgraded back to Lion the second time. I went from Lion back to a clean install of Snow Leopard back to Lion and then I had the problem with it not waking from sleep. The first instance with Lion I had no problems. So I decided to go back and do another install of Snow Leopard and the problem stayed with me. I am now on 10.8.1 and the problem remains the same.

I have, kind of, solved the sleep problems by putting hibernatemode at 25. This has allowed me to wake the computer up without a hard reset, but when I do wake it up it makes that hard drive spinning noise twice, almost as if it is waking up twice. Then, back to 2gb unless I reset the ram. I am going to take the case off tomorrow and just make sure everything is ok in there, but other than that I am just hoping it's not the logic board as my computer is a few years old now. I may also just throw a 4gb into the one thats working.

Memtest has found no problems either, both with 2gb and 4gb showing.

Thanks for the help everyone, this is really driving me nuts and answers are hard to come by.

Sorry I have no idea about your waking problems but I don't think it is related in any way to the OPs problem.

Simple fact is RAM is hardware. It is either good or bad, it either shows up or it doesn't. There is No software involved with the detection of the amount of RAM in the system. The Hardware in the system is recorded by and reported to the OS by the firmware and the System Management Controller. No operating system or change in it will change the state of whether or not the hardware is recorded and reported.

So that leaves the SMC which I guess could go bad in some way. But then if it did the only way to fix it would be to change out the Logic board. The same for a bad RAM slot and or bad slot to Logic board connection.

Simple tests.

1) Take an external and make multiple partitions on it. Install all version of OS X that you have access to and will lrun on your model Mac each in there own partition on the external. Run all of them one after the other then boot back into the OS on the internal. Does all the RAM show in one and not the other?

2) When the system is reporting only RAM from one slot run the Apple Hardware Test, either from DVD disc supplied with the system or from over the internet. That will take all inbstalled versions of OS X out of the picture.

As to the person that stated Apple change both RAM and Logic board and the problem continued. Apple probably changed one and not the other. Or that person is flat out lying. ( Oh I forgot no one lies on the Internet).

By the way I am a Hot 17 year old looking for Love. And I have a Bridge I'd like to sell to someone.

drjingles31 wrote:

I thought he might be lying, or apple for that matter, so I took it with a grain of salt. I will continue the hunt tomorrow as I need my computer for some work tonight.

Are you by chance interested in the Bridge? Ha Ha 😁😁

drjingles31 wrote:

See, the thing is I am in Nigeria retreiving money left to me from my uncle. I would be willing to mail you a check. Send me your info. I wish to purchase your bridge.

😁😁😁😁

Have a good Night and thanks for the Laugh.

I just wanted to comment that I have a Mid 2009 MacBook Pro 13" and I have had a similar issue. I think that the PRAM reset fixed the sleep issue, and currently I am actually on 10.8.2, not 10.8.1.

Anyways, to get to my point, I have a bootcamp partition on my harddisk... interestingly, on the bookcamp partition (running Windows 7 Ulti) it ALWAYS recognizes all 8GB of RAM, not just the 4GB in one slot, and the performance clearly shows that there are 8GB of RAM running on the W7 side of the computer, not 4GB. Occasionally (not all the time for some reason) with a PRAM reset I can get OSX 10.8.2 to run with all 8GB of RAM (and it certainly runs as though on 8GB as opposed to 4GB), but this is rare and once the computer is restarted the RAM is back to only 4GB.

Again, despite the issue with the RAM in 10.8.2, when booted to Windows 7 on the SAME computer, I have all fully-functioning 8GB RAM.

I'm going to say that this is probably not a Logicboard error, but an OS error instead. I wish I knew how to fix this, or better yet, that Apple would patch it!

Sorry I don't, but I believe they have replacement parts for that. Otherwise, u may have jerryrig the the memory in space so it doesn't move.

In retrospect, I don't even think you have to remove the ram, just LOOSEN the 4 screws around the Ram holder. Don't take them out.

I hope this works for everyone. As of this morning, I have a full 8 gb and it feels great. Normally at room temperature, i get 4 gb everytime i start up.

I have a mid 2009 15" Mac Book Pro. After I installed 10.7 it was running very slow so I purchased 4+4 RAM and installed it about 6 months ago. It worked great... for a while. Then it wouldn't recognized one bank of the 4 GB RAM (purchased from Apple). Living in Northern CA I have no authorized Apple repair options so I took it upon myself to figure this out. I have to say that by removing and replacing both 4GB RAM into the RAM banks, lossening the screws that hold the bank in place, and restarting my computer, it now recognizes all 8 GB of RAM. My fingers are crossed this is the DEFINITIVE fix that quadturbo suggests. THANK YOU!

Thanks Patricia, I'm glad this is working out for you. As far as my computer goes, it has been reading all 8 gb of RAM no matter how many times I restart, even after running graphic intensive applications (heating the macbook up quite a bit).

Just to add a little to the above tutorial, I would advise loosening all 4 screw by about 1/2 a millimeter. If you look carefully, there are these tiny "gold rods" that stick straight out and retract when you push on them. The screws should not exceed those rod's length.

I have asked some hardware design engineers, and they don't seem surprised that this is happening to my 3 year old beloved macbook pro. The heat is DEFINITELY an issue (see my above post) and hence the new macbook design with soldered ram. But they gave me a bunch reasons, warping circuit board, solder melting and loosening contact, etc. I really have no idea why loosening the screws work aside from the fact that it may allow the circuit board to expand.

I hope this fix is more less definitive until the computer really just dies.

Looking good so far - your advice is the first that I've found that suggests a solution with good reasoning behind it and, so far, looks like solving my problem. *Thank you*.

I have a mid-2009 13" MacBook Pro which has manifested:

• sproadic video corruption - nothing debilitating, just a temporary visual glitch

• Bank 1 of my RAM flaking and refusing to recognise known good memory

• the 'black screen of death' - return to the user login window, sleep the Mac, reawaken to find a black screen that nothing short of a hard reboot will solve

So far, so good…

I've recently had the same problem with my mid-2009 13" MacBook Pro. Top slot works fine, bottom slot doesn't. Often fails to wake from sleep with both slots filled due to detecting/loosing bottom slot after being moved around.

I'll try the fix with loosening the screws this weekend and report back. Makes sense that heat could cause an issue over time. These things run hot. So glad I found this thread. Should save me hours of troubleshooting.

Hi

I cannot believe that so many people have had the same issues with the same computers and apple have not made people aware of it. I have taken my computer to 3 "geniuses" and none of them were able to help. They said replace case as it may be magnets, and said it was error in sleep file etc etc.

I have tried to do this and it seemed to work for a day. The next day.... as i had ordered new ram before i found your post, i upgraded to 2 new 4gb ram so i switched them. When i first switched on it recognised all 8gb but now it is only recognising 4 and it has done a shutdown after waking from sleep mode twice. Do other peoples also do shutdowns / start up when they open up after sleep?

Just after any insights as to what i may have done wrong.... Do you think the screws may be too loose? or not enough? Any advice from others that have succeeded would be appreciated just to reduce my trial and error time!

I am so glad for this post and effort mad eby people as i was searching apple for what computer to replace my beloved 17" with when i looked this up, will hopefully delay the expentiture for a while.

I have tried numerous fixes, many of which temporarily got my full RAM back online. Finally, I tried this fix (loosening the screws just a tad), and I have had no issues for almost two months. Thank you for this!

MacBookPro5,1

Intel Core 2 Duo – 2.53 GHz

4 GB RAM