macbook won't boot with 4gb

I remember one person reported that kind of behavior with a pair of PC2-6400 SODIMMs. It would work with either one or one 512 MB with the new 2 GB. Perhaps a mention of what brand and type of memory?

I know it might sound silly, but have you made sure that the RAM is pushed in far enough? I had a similar problem once, and it was because the modules were not seated properly in the bay.
Failing that, I'd send the modules back for a replacement.

Take out one at a time and try it. You can put the old, known to be good ram in the empty slot. If it boots with one but not the other, return the bad one.

+*I remember one person reported that kind of behavior with a pair of PC2-6400 SODIMMs. It would work with either one or one 512 MB with the new 2 GB. Perhaps a mention of what brand and type of memory?*+

I have actually seen a number of posts from people using faster rated memory encountering this problem.

I installed 4GB in my new MacBook before I even turned it on the first time this January and it worked like a charm. It was store-brand by OWC http://eshop.macsales.com/item/Other%20World%20Computing/53IM2DDR4GBK/ and was less than $100 at the time.

Crucial is a good brand. I've used it in several PCs before. But maybe it just isn't friendly for the MacBook.

I had this problem when fitting my RAM, just push it in until your fingertip is nearly bleeding -that got it going for me....

Also check that your machine supports 4GB, as some of the early MacBooks arent supposed to...

All the best,

Jon

Not being rude but the manual of your MacBook does say the Motherboard only supports upto 2gb. 4gb is too much for the LogicBoard to share out...

...the manual of your MacBook does say the Motherboard only supports upto 2gb.

Not so. According to the manual in front of me:

"Both memory slots can accept an SDRAM module that meets the following specifications:
...
512 MB, 1 GB, or 2 GB"

That's not total RAM, that's per module.

(That's the same model as I'm using with 4GB of Crucial RAM).

All I get with the 4gb is a blank screen and a solid on sleep light.

I assume that means you are also not hearing the boot chime?

"Black screen, power LED on - POST or BootROM failure" - from: http://docs.info.apple.com/article.html?artnum=303363

As you say, the above article indicates it is not bad RAM. However, if no chime, your MacBook is failing its self-test (POST).

crucial brand pc5300 2x2gb

Check that the Micron labels show:
"2GB 2RX8 PC2-5300S-555...
...CL5"

The modules each have 8 black component chips on each side? Also check to see what is reported by System Profiler in its "Memory" and "Diagnostics" sections.

There have been very rare reports of mislabeled RAM. If you were accidentally shipped 2x4GB that was mislabeled as 2x2GB, perhaps that might account for the problem.

I had the same issue with my new MacBook. The 4GB 2x2GB kit from Crucial.
The MacBook will not boot with both 2GB DIMM's installed. It works fine with 1.

I tested both 2GB DIMM's they both work just not together!

I am beginning to believe that some of the MacBooks out even with the new processor like mine will not support 4GB even though they are sold to do so!

This is not a great way for a new Mac owner to start!

Afraid that I have the same problem others have cited.
I also purchased a 4Gb pair from Crucial.

I did call Crucial Tech Support and they are aware of the issue, but at this time they feel it is a Apple Hardware problem.

I can pair up one 2Gb module with the .5Gb module from the system in either slot combination and everything works well...... just not with both 2 Gb module installed.

Has anyone found a memory supplier that works??

So that no one is misled by my above mention that my 4GB of Crucial works fine, and to provide further info, my Crucial RAM was purchased earlier in 2007 prior to my owning a computer that would accept 4GB of SODIMMs. I thought it was cheap, but it got cheaper since then. Funny thing about that:))

MacBook is a production week 46 of 2007, U.S., while my 2x2GB of Crucial Micron RAM (with 8 black chip components on each of two sides) is from Micron's production week 22 of 2007, country of origin U.S., and
Crucial labeled #CT25664AC667.16FE

also Micron labeled #MT16HTF25664HY-667-E1
2GB 2RX8 PC2-5300S-555-12-ZZ

Good luck with it:)