8 GB RAM i MacBook Pro (Santa Rosa eller senare)

Okay, I'm going to clear up some of the questions for this since it appears there is SOOOO many threads being created about this.

YES 8GB WORKS IN THE MACBOOK PRO EVEN IF APPLE SAYS THEY DON'T OFFICIALLY SUPPORT IT.

You have 2 options above 4GB:

6GB (1x2GB/1x4GB)
8GB (2x4GB)

FAQ:

Will my MacBook Pro support 8GB?
- Only the Santa Rosa and Penryn (MacBook Pro 3,1 and 4,1) can support this much memory. The MacBook Pro 2,1 only supports upto 3.25GB ram accessible so adding in 8GB wouldn't matter since you can only access >4GB. Currently, OSX Leopard (10.5.x) seems to have trouble accessing above 4GB of ram. It is unclear if this will effect users attempting to use 6/8GB in their MacBook Pro.

How do I know when my MacBook Pro was purchased?
- Read this: MacBook Pro - Mac Guides
If you fall into Rev D or Rev E specs, you can support 8GB.

If I add 1x4GB and 1x2GB, totaling 6GB; or just using 1x4GB; do I lose dual channel?
- Yes, you do lose dual channel.

Is losing Dual Channel a huge performance hit?
- Not really. It all depends on what you use it for. If you're doing a lot of modeling/rendering, dual channel might be a great help. For an average user or someone who runs memory hungry apps such as Virtual Machines, it is not much of an hit.

Isn't Leopard (10.5.x) 32-bit?
- Yes and No. Leopard uses both 32 and 64-bit framework. It is not entirely just 32-bit therefore it can access and use all the 4+GB ram. Unlike Windows XP (for example) it is completely 32-bit and cannot read/write/access anything above 4GB. If you don't believe me, its on Leopard's page on apple.com.

- Currently, there is some problems with OSX Leopard (10.5.x) to allocate more then 4GB ram without going into swap. Initial tests shows OSX Snow Leopard (10.6) to not have this problem. Further testing is being done in Page 4 of this thread.

Will 6/8GB be supported on systems other then MacBook Pro and Mac Pro?
- In theory, the Santa Rosa and Penryn MacBook and current versions of the iMac should be able to use the 6/8GB extra ram. However, until we have a guinea pig to test it, it is just a theory. If anyone does test it, please tell me and I can update this FAQ.

There are no 4GB parts available yet in the 1066 MHz, "PC-8500" specification, but the MacBooks only support a total of 4GB of RAM anyway. It appears, but is not definitely confirmed, that the new machines will not ever be able to support 4GB parts for a total of 8GB. In the past, Apple has sometimes listed maximum RAM limits that were later extended as newer RAM densities became available. As post Santa Rosa-style architectures, the new MacBooks can fully address all 4GB of RAM, but there is no reason for believing that they could address more than 4GB.

Finally, NVIDIA confirms another interesting tidbit that had been circulating already. These new chipsets officially support 8GB of RAM. Prior to this, it appears MacBook Pros were limited to 4GB of RAM. This would be a welcome change for those who use their MacBook Pros for memory intensive tasks. This being said, we haven't yet heard of anyone who has successfully installed 8GB of RAM in their new MacBook Pro.

CONCLUSION
The 6GB configuration produced essentially identical benchmark results to the 4GB configuration in our 2.8GHz MacBook Pro. The difference ranged from -.5% to +1.7% or an average difference of +.28% or less than 1/3 of one percent. I call that negligible. Or, in other words, you should have no worries about a speed penalty imposed by non-matching memory modules and loss of interleaving.

And when you consider the 6GB configuration potentially means less virtual memory swaps, then the only consideration is the cost. Maybe instead of ordering your MBP with the $500 128GB SSD, you should save your money for a 4GB memory module.

Looks like a winning combination to me. You can never be too thin, too rich, or have too much memory.

NO, 8GB WON'T WORK
Just for fun we tried the 8GB configuration (2 x 4GB). Though the MacBook Pro will boot and Activity Monitor sees all 8GB, there are serious operational issues. For starters, if you use anything beyond 4GB of real memory, the MBP goes into "molasses" mode. And if you manage to quit out of the memory hungry app, the reported amount of real memory in use does not recede. At a certain point, our operation was so crippled that we had to push and hold the power button to force a shutdown.