Memory upgrade possible?

Hi this is my first post, I just bought the new Macbook (MB402LL/B) from BestBuy, where I work.

First, the title is a little misleading. I know the memory is upgradeable...
But, on the box it says expandable up to 4 GB - which I am leaning is incorrect.

I work at the Geek Squad and am a Computer Engineer working with Solaris and various different hardware platforms and OS's --- Im hardly a newb and have tried several things to get my new Macbook to accept the total 4GB it advertises. So your help would be appreciated.

So I purchased two 2GB Kingston certified PC2 5300 apple memory chips (4GB total). I installed both, and immediately got three beep codes.

My troubleshooting and results:
1. I reseated the memory (must be dozens of times) with no resolution.
2. I removed one memory chip, the system booted up fine. Thought I might have a bad memory chip... So I removed the now working chip with the one I previously installed (swapped them) The system booted up fine...
3. Reinstalled the previously working chip and attempted reseating it again - no joy.
4. Replaced the memory chips alltogether - no joy.
5. Interchanged one memory chip between both chip modules/slot... both slots worked with one 2GB chip in each. Doesnt appear to be the mobo..
6. Reinstalled a single 512MB chip (factory chip) with 2GB chip (total of 2.5GB) - System boots fine.


How do I get to 4GB? I didn't see any sort of firmware update with the Mac Updates.. has anyone else had this problem?

 

Because jamming a DDR2 chip into a DDR3 slot sometimes works, must be how I got the macbook to post several times, brilliant. Just FYI, the slots are different, I would have figured that out a long time ago. And hopefully my trust in this forum is warranted.

I saw 4 replies so quickly I thought there might be an answer already, hopefully someone else has seen this before.

 

Thanks for the advise.

I have tried other modules. Best Buy doesn't carry a lot of slower only memory.

I tried some 800Mhz RAM (667, etc compatible) and the only way I could get it to work was by using one 667Mhz chip that came in the system and the 800Mhz. Apparently mac's only look to verify one chip is present that meet its specification requirements then allows the other to work at the compatible speed.

I will get some more and update in the event anyone else happens across this problem.

Thanks again all.