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

Thanks, dude. I just ordered a new laptop and I came across this thread trying to find out what to do with my MBP while I wait for my new one. I loosened three ****ing screws (the fourth was stubborn and I stripped it) and I'm back to 8GB. You're the man, quadturbo. Thinking about cancelling my order, but hard to say no to new hardware.

quadturbo wrote:

I believe I have found a DEFINITIVE solution to an identifiable problem. I have a Macbook Pro 13" 2010, with 8 gb ram. In the last 6 months, I have had Bank 1 (4 gb) disappearing on me intermittently. In the last two months, I had consistent loss of 4 gb of ram, especially after restart. When I start cold (after 24 hours), it recognizes 8 gb, but if I restart, it recognizes only 4 gb. I would stick the macbook in the freezer for 10 min. Of course, I get 8 gb.

So what the ****?

I have gone through every thread google has to offer. No solution, except that the best explanation was that circuit board was getting old. It explains why Apple created new vents for the new Macbooks. I also believe they soldered in the ram for this exact reason.

So I got sick of it and opened up the macbook, unscrewed, removed, cleaned out the fan, unscrewed the circuit board removed the Ram. I even unscrewed the 4 screws around the plastic RAM holder. I cleaned everything out with 91% isopropyl alcohol and everything inside the RAM holder and the ram itself.

I tested each RAM in each slot alone and carefully turned the computer on. 4 gb as expected. Both banks worked. Both RAM functioned fine alone in each of the banks.

So what the ****?

I popped both back in.....8 gb. Restarted it. 8 gb. I did this 10 x. Every time 8gb.

So I thought it was because I did a great "cleaning" job. I screwed everything back in, circuit board, RAM "holder", etc. Restarted....7.75 gb. !?

Restarted again.... 4gb?! DId this 10x, 4 gb.

What the ****?

I opened everything and LOOSENED the four screws around the Ram HOLDER.....

8 gb ever since!

I believe with time, the awesome heat from the macbook pro eventually warps the circuit board. My macbook was just under 3 years old and started to have this problem. The four screws holding the ram holder in start to tighten up with heat and somehow it does not recognize one bank. That's why when I freeze the macbook, it gets the other bank back. By loosening the screws, it allows the circuitboard expansion with heat.

Anyways, I hope that helps.

Thanks quadturbo! If you still check this thread, has your fix lasted?

I posted an article to my site detailing the fix you suggested to hopefully help others:

https://people.cam.cornell.edu/~zc227/extras/mid2009mbp_RAM.html

I'm still following this thread and yes the fix has lasted. Skimnc, great write up, I'm glad this helped alot of people. I gave my mac to my sibling who games on it (heat galore). After restarting, it still reads all the RAM!

I really like iveney's explanation and his success confirms my theory of the board warping and distorting the contacts.

As for me, I moved onto a Retina 15" 16 gb. I liked the fact that they solder their ram in. And its kind of slimy that Apple probably internally knows about this problem. The retina is very solid.

Thanks skimnc for the dedicated page. I also have a temporary fix and it seems the problem is resolved. I wrote a blog post on this, with some pics:

http://blog.ivansiu.com/blog/2014/05/28/fix-mid-2009-mbp-ram-not-recognized-issu e/

For those of you that still want to stick to the old MBP, the fix shall last for a while. But I do recomend you backup all the files and prepare to migrate some day soon.

Thanks to all the posters on here. I just wanted to share my related story.

I had the same issue, and fixed it by loosening the screws. Then that stopped working, so I retightened them. After a while I had to loosen them again...and on and on. Then I started getting freezes and discolored screen locks just from tapping my laptop. Reading online I was wondering if maybe this was my HDD connections and I needed new cables.

So I opened up the back with the laptop running (shame on me, right?), and tapped around on various components trying to duplicate what would happen when it was all closed up (if I would even tap on the desk too hard the thing would lock up and require reboot). I tapped on all the cables. Nothing. Then I tapped on the RAM bracket, and everything went pink and blue and locked up. So I loosed the RAM bracket screws, removed the RAM, retightened the screws, and replaced the RAM and rebooted. With the back still open, I logged in and saw all the ram (8GB) present. Then I tapped the RAM bracket, and everything kept running - no freezes lockups.

Sadly, given my experience, this issue will surely come back. I'm in the process of getting a new laptop, so that I won't run into this issue incessantly in the future. Nonetheless, it is frustrating that having had this laptop in the Genius bar multiple times for this issue, there has not been a fix.

All that to say, if you're trying to salvage your MBP, keep tweaking that RAM bracket. No need to replace RAM, logic board, etc. Just keep tweaking - that's all I can suggest. I do think as was said above, that this is related to the MBP getting really warm and things shifting, but not sure how to fix it permanently.

I have exactly the same problem. Second RAM slot not recognised after installation of Mountain Lion. Refuses to wake up after closing the lid. Only way to get mac working again is long presses of the power button to reboot. This problem has continued for about 6 months. The geniuses at Apple are not very clever because they were completely unable to assist. I replaced all the RAM but to no avail. I will be trying the screw loosening thing. Questioning whether Apple products really are worth all the money now.

I'm having this same problem ... except for now my computer will only recognize 1 memory stick (2gb RAM).

I have a macbook pro mid-2009, 2.26ghz

I have 2 x 2gb of Ram; one in each slot.

Slot Bank 0 recognizes the 2GB of RAM; Bank 1 says "empty" but there is actually a 2GB RAM stick there.

I opened up the back of the computer and switched the RAM sticks to make sure that each work; same result. It appears then that Slot Bank 1 has gone bad.

Now I'm thinking I need to replace the logic board? But petepete0pete said that the Genius bar replaced his logic board twice and the problem persists? What is the fix for this? Can I replace just the RAM slot bank? Do I need to replace the logic board memory?

Thanks

I have MBP 13" mid 2010, i think i have been running it on one ram for the past 2 or 3 years.
I can connect to all the stories about sleep issues because when the MBP was around one years old they started, i used all the tricks clearing smc, clean OS X etc.. finally the sleep issues stopped i guess it was then memory bank 1 became "empty".
Found out about this problem when i was going to upgrade my Ram from 2 GB (thought there were two 1 GB Ram modules but they were two 2 GB modules in the computer) to two 4 GB modules.

I was able to fix this by stuffing folded shopping receipts on and around the two modules(do on your own risk) but sometimes the computer wont wake up from sleep because connection is lost.

What I find weird about this is that if I remove one module the computer wont start.. so there must be some connectivity?

As crazy as it sounds, I tried this, because I upgraded my RAM to 2 x 4GB sitcks from the original 2 x 1GB and I was getting errors in the bottom slot ( not sure if that is slot 0 or 1) ad described by others, except it would not even recognise the RAM and I was getting beeps on startup and no booting, then hanging and failing to restart from sleep mode,

This fix seemed to work. Running a hardware diagnostic overnight to check RAM sticks as well. Hopefully this will work because if not I will be stuck with 4GB in one slot only 😟

So, given that the 1GB stick seems to work fine in Slot 0, and 4GB stick in slot 1, how much of a performance hit would I expect to get if I decided to run with it configured that way? Or should I just run 4GB in slot 1?

I paid $294 on Amazon and he's supposed to be giving me a $40 credit for mailing him my old logic board;

http://www.amazon.com/gp/product/B003CO1NHA/ref=oh_aui_detailpage_o03_s00?ie=UTF 8&psc=1

I found a youtube video with step by step instructions on how to replace it.

Thanks for investigating and posting here. It was helpful for me and my MBP mid 2010 also. Same issue and symptoms. I have loosened the screws of the memory brackets and kept the computer backside lid open. Not seen the problem. Hope this is resolved.

We had the same issue, the system not recognizing the RAM.

If you are at this point, you have already gone thru how to remove RAM.

I'll just go in

We have 2 computers that we " did surgery" on. A 2009 macbook pro and a 2011 macbook pro.

When both computers said one of the slots were not recognized, we delved in a bit further.

What we did :

1. Do a proper shut down of the machine( from the apple drop down)

2. Unscrew back.

3. Remove the new ( not working) RAM..

4. Blow out the slots for any dust bunnies.

5.Re-insert RAM.

6. Unscrew ( just1 turn) all 4 screws around memory slot.

7. Screw back - back on.

8. Hold down Option-Command key with power button.

9. Release once screen turns gray

10. Check memory- and voila!

Thanks to the two different people who posted in the forum the different actions listed above.

Not sure which one made the system recognize the RAM, but it did.

It's also possible that the RAM itself is bad. Is it 3rd party RAM?

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.