Exams are now (almost) over, and I thought it was time for a short post, first post in a while - life has kept me very busy and studying electrical engineering is very time consuming.
I was doing an upgrade of my friends Unibody MacBook Pro (2.66GHz), medio 2009. We were going to upgrade the ram from 2x2GB to 2x4GB, since one block went bad earlier.With the bad block inserted, the mac would always fail to wake up from sleep and removing the bad block solved the issue. Obviously 2GB ram wasn't enough, so a RAM replacement was needed.
Turns out after both blocks were inserted, only one of them were detected, resulting in a total RAM amount of 4GB. We didn't understand why only one was discovered, this version of the MBP was supposed to support at least 2x8GB 1067DDR3 RAM. We also went for "Corsair MAC" branded memory, so it was supposed to work just fine.
We tried swapping and reaseating but nothing helped. As usual, we started googling the problem and it turns out we aren't alone with this issue. Most forum posts suggested it was related to a faulty motherboard/logicboard. A few suggested an EFI firmware update would solve the problem, but we were already running with the latest 1.7 update, so sadly that couldn't be the issue. We also reset PRAM (Command (⌘), Option, P, and R), but that didn't help either.
After a few more searching, we stumbled upon an interesting thread, with someone having a very similar issue:
Dissapearing ram and sleep issues - also with an Unibody MBP mid 2009 (The thread says version 5.5 is, maybe this is a mistake?)
The user [QuadTurbo], from the forum linked to above, suggested the following. It sounded quite silly at first, but we tried anyways:
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.
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.
Guess what... That solution worked PERFECTLY - all 8GB ram were now detected! I would have never expected a few screws would solve such a strange issue.. Maybe it is not only an issue with the 5.3 series of UMBP?
Please let me know if this issue can help you!