MacBook Pro RAM installation problem

I have a 2.4 GHz, early 2008, MacBook Pro. Came with 2 GB RAM. I went out today and got two Kensington 2GB DDR PC2-5300 667 MHz sticks - to make it 4 GB of RAM. When I put the two news sticks in, the computer will turn on - but just have a black screen nothing happens. When I put my old RAM back in, everything boots up fine. Here is where it gets weird: when I put one of the new 2 GB sticks (either one) in along with one of the old 1 GB sticks it boots up fine and shows it running 3GB of RAM. Why can't it work with 4GB??

Tags: installation, macbook, memory, pro, problem, ram

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Permalink Reply by Mad Max on April 4, 2009 at 6:49pm: You may have somehow ended up with a model that only accepts a maximum of 3, which I believe the generation before the last one had... root around the Apple site, it has a list somewhere (that I forget how to get to lol) of how much and what type of RAM each of their models can take. Check for the model number of your MBP and match it against the list to be sure. If it says it takes 4 but isnt, I'd book an appointment with a Genius if you're close enough to an Apple Store for it to be worth it, they'll be able to shed more light on the matter.

Permalink Reply by Cookenstein on April 4, 2009 at 6:50pm: Something to do with your two new sticks. For whatever the reason not seeing in pairs. Ram is a testy little science.
This comment comes direct from Support at Apples website concerning your specific model.
You can use Small-Outline Dual Inline Memory Modules (SO-DIMMS) that meet all of these criteria:

* PC2-5300
* unbuffered
* nonparity
* 200-pin
* 667 MHz
* DDR2 SDRAM

You can use RAM module sizes of 1 GB or 2GB in the top or bottom slots.

DIMMs with any of the following features are not supported in the MacBook Pro (Core 2 Duo) notebooks: registers or buffers, PLLs, ECC, parity, or EDO RAM.

Note: If you do install a 2 GB SO-DIMM in both the bottom and top memory slots of the notebook, the About This Mac window and Apple System Profiler will both show that you have 4 GB of SDRAM installed. However, Activity Monitor and other similar applications will reveal that only 3 GB of SDRAM has been addressed for use by the computer.

Permalink Reply by Alovebaby41 on April 6, 2009 at 7:11am: I heard about this problem on twitter and really was wowed about this issue I have a Macbook and I upgraded it to 4GB as well and I used Kensington ram and have no problems with it maybe you didn't get the right kind of ram for that motherboard or one of the sticks isn't campatable but I have never heard of Ram being not campatable. I hope that somebody can help you and find a solution to your problem.

Permalink Reply by rea S⃣ n555 on April 6, 2009 at 9:08am: I have the same specs as you do
im using ram from apple,this is how it should look when your running on 4 gigs of ram
here is the link for the ram i bought,it works perfect but costs money http://store.apple.com/us/memorymodel/ME_15_2_4_MBP_PREV

Permalink Reply by David on April 6, 2009 at 8:52pm: Thank you all for the help! I brought my MAC to the Genius Bar, they determined it was bad RAM, I ordered new RAM from newegg, will be returning the bad RAM to Best Buy.