MacBook Pro thinks a memory bank is empty when restarted?

[wheels]

Hi all,

I was wondering if you guys could help me with my MacBook Pro. Forgive me if this is the wrong place to ask, I'm new here.

I have a mid-2009 13" MacBook Pro, with two 1-GB RAM cards filling the two memory banks. Whenever the computer is restarted, the blank white screen comes up once, and then it appears to shut down again and the white screen will come up again, before showing the Apple logo. After it starts up, one of the memory banks is marked as empty (as far as I can tell it is always BANK0 that remains full, and BANK1 that appears empty). The other bank is definitely not empty however.

I thought this might be a PRAM issue, but when I reset the PRAM (Command+Option+P+R at startup) this just mimics the regular start up behaviour (the two "white screens"), and still shows one of the memory banks as empty.

In order to "fix" this problem, I have to take out the RAM and reinsert it. Switching the two RAM cards does not appear to change which memory bank is empty, so I think the actual RAM cards are okay.

I've done a bit of research, and I think the PRAM battery may be dead. However I've also read that my model of the MacBook does not have a PRAM battery, but it is actually either housed inside the main battery or just a capacitor (I've read conflicting things...).

So I was just wondering if you guys had any thoughts on this or advice to offer? These problems cropped up around the time that I installed Lion, if that helps. I am now running Mountain Lion.

Thanks a lot!

 

[chscag]

A PRAM - NVRAM reset won't help when that problem occurs. Two things can cause it:

1. The modules themselves are bad or intermittent.

2. The memory slot (Bank 1) is defective. It could be loose on the mother board (logic board) or the slot contacts could be bent or worn.

It appears from your description that it's the slot itself that's causing the problem not the modules. Unfortunately the only cure for that is to replace the entire logic board. An expensive repair.

 

[wheels]

Hmmm that's not good. But why is the problem so easily fixed? Why does the restart cause it to reoccur? This is reminding me of the days when I needed to blow on cartridges to get them to work...

 

[chscag]

But why is the problem so easily fixed?

Easily fixed? Having to open the machine and removing, reseating, a memory module is not exactly what I would call an easy fix. It's definitely a hardware problem with the slot itself. But you can try this:

Buy a can of compressed air at a store which sells computer accessories and use it to blow a couple of short blasts of air into the slot. If the slot is dirty that may clean it out. However, if there's any corrosion in it or if it's loose on the logic board, the only remedy is to replace the board.

 

[freidy]

Loosen the bolts around the RAM slot to fix the issue

I had the same problem and found the answer on macrumors. Slightly loosening the 4 bolts that are around the RAM slot by about 1 rotation did the trick for me. Here's the thread where I found the answer. I'm just reposting so that others can benefit from this info.

http://forums.macrumors.com/showthread.php?t=1360315

 

[chscag]

Thanks for sharing! Hopefully this thread will come up in a search for those who have the same problem.