New MacBook Pro Is Unstable With 8GB RAM

Testing suggests that the New MacBook Pro hardware can handle 8GB of RAM; however, there are OS-level limitations that cause instability.

Luke from iFixIt.com tested the new MacBook Pro with 8GB of RAM and posted the following on MacRumors

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We did some more testing and found some interesting things. We have not succeeded to go beyond the 4GB limit with any OS X GUI app. With a C app (eatmem) that does not use Apple's APIs, we were able to allocate 8 GB and have it reported in Activity Monitor (and top).

The C app was able to allocate up to 8 GB without paging to disk. However, OS X is not happy running at or above the 4 GB limit. Performance is very erratic, and we crashed OS X and Parallels multiple times.


8 GB allocated, the system crashed shortly thereafter.

Interestingly, when we booted Ubuntu on the machine it only reported 3 GB memory total. We don't have an explanation for that.

Overall, our testing showed that the system is unstable at 8 GB of RAM. Parallels takes forever to load, even when using
We then yanked a chip to do a comparison with 4 GB. With a single 4 GB chip, everything seems happy.

We then added a 1 GB chip for 5 GB total. We were able to get GUI apps to use all 5 GB and the system hasn't crashed on us yet. It will take more testing to determine how stable this configuration is.

We suspect that this testing implies a two things:
1) The hardware can handle a 4 GB chip without any problem
2) There are OS-level limitations with 8 GB RAM on these systems.

Luke Soules
iFixit Labs
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