Memory upgrade problem---MacBook Pro

I have an early 2008 MacBook Pro with 2gb of memory--one gb in each slot. 4 gb possible total.

I recently ordered an upgrade of 2 - 2gb modules but when I installed them my computer would not start up. I tried re-installing and switching slots to no avail. I discovered that I could start up with one 2gb module in the lower slot only and also with one 2gb module in the lower slot and one 1gb module in the top slot (total 3gb) but in no case will it start with two 2gb modules.

I called product support where I purchased the memory and they had me reset the pram which did not solve the problem. They sent me 2 new 2gb modules which don't work either.

The problem appears to be with my computer. What and why?

You didn't mention which kind of memory you purchased but here is what your early 2008 MacBook Pro takes:

Maximum Memory 6.0 GB (Actual) 4.0 GB (Apple)
Memory Slots 2 - 200-pin PC2-5300 (667MHz) DDR2 SO-DIMM

i purchased what you described from OWC 2-2gb 200-pin PC2-5300 (667MHz) DDR2 SO-DIMM CAS 4 High-Performance tuned low-latency

Oldsoul said:

i purchased what you described from OWC 2-2gb 200-pin PC2-5300 (667MHz) DDR2 SO-DIMM CAS 4 High-Performance tuned low-latency

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That's the correct memory, and memory modules from OWC are of the best quality. We always recommend buying from them or Crucial.

The problem appears to be with my computer. What and why?

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I've seen problems from other users which match the problem you're having. Several users described having to disassemble their machine, remove the logic board, and adjust the screws that held the memory slot connectors in place. One member stated that after he made the adjustments, that the slots began to function normally again. Other users reported the slots just would not function properly no matter what they did.

Your machine is old and it's possible that heat build up over the years has put a lot of strain on those module connectors. Sorry but that's the best I can provide you with based on what I've learned from other users who have posted to our forums. You might wish to do a search in the Apple User Discussion Forums which are massive compared to ours and have many more users and lots of very experienced users.

Thank you for your detailed answer, I will follow through on the Apple User forum.

What is interesting is that the upper slot will read a 1 gb module but not a 2 gb module. Apple replaced the logic board 2 ½ years ago under warranty, part # 605-1795, could that be the problem?

What is interesting is that the upper slot will read a 1 gb module but not a 2 gb module. Apple replaced the logic board 2 ½ years ago under warranty, part # 605-1795, could that be the problem?

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That's interesting. Although I'm sure Apple would have replaced the logic board with an exact replacement. But, the logic board that Apple replaced yours with was very likely a refurbished board not a new one. But again, that shouldn't matter as they check and test their refurbished parts very carefully. Anyway, be sure to mention that fact when you get on the Apple Discussion Forum. And let us know here if you resolve it.

I have posted my problem with Apple, I will let you know if I find a solution. Thanks again!

Update: Nothing worked, all memory that my Macbook pro will accept is 3GB, 2GB in the lower slot and 1GB in the upper. I tried 4GB of regular memory instead of low latency and it did boot up but within a minute it did a "panic" shut down. I give up and will have to be happy with 3GB total. Thanks for your help!