No 8GB RAM on the new 15" MBP's? Why?

in Current Mac Hardware edited January 2014
Just wondering.... It seems the new MBP's all use the same kind of RAM, why don't the 15" support the 4GB chips? Do they use an older chipset or something? I REALLY want 8GB RAM and am seriously considering selling my 1 1/2 year old MBP which only supports 3GB RAM to get one of the new MBP's. However, I don't really want a 17" screen on a laptop as I think it's too big. 15" is perfect for me. The new 17" with 8GB RAM is just too much money.

It would have to be a chipset thing, wouldn't it? Like with my current 15" MBP... Like I said, it only supports 3GB RAM, even though there are two slots and each slots support a 2GB chip.


  • Reply 1 of 4
    messiahmessiah Posts: 1,689member
    There was talk that the new unibody MacBooks could work with 6GB of RAM (1x4GB + 1x2GB), but that nobody had tested them with 8GB of RAM due to the insane cost of the 4GB parts.

    Phil introduced the 17"ers CPU as a 'new generation' of Intel Core 2 Duo processor. Perhaps that has something to do with its ability to support 8GB?
  • Reply 2 of 4
    Never mind... Found some other forums with this question asked and discussed to death. Seems the new 15" MBP's support up to 6GB RAM. The best theory I found for why this is the case is this: When the Mac boots up it checks two things 1) How much RAM is installed and 2) how much of it is usable. The graphics memory seems to be given addresses from 7GB and up, so two 4GB DIMMS will cause the Mac to do the following: First it sees a 4GB DIMM and registeres that the entire DIMM is usable - htne it sees the other 4GB DIMM and registers that it causes an overlap with the allocated graphics memory space, so it registers it as unusable. It still registers that there is, in fact, 8GB RAM installed - so that's what OS X reports. When it find one 4GB DIMM and some other size DIMM it registers that the 4GB is usable and that the other DIMM is usable too, since it doesn't conflict with the graphics memory space.

    Installing 8GB causes the machine to come grinding to a halt when using more than 4GB RAM, because the OS sees 8GB, but when trying to access memory from addresses of 4GB+ it can't find the RAM for it, since the DIMM isn't used - so it has to start swapping like crazy.

    Oh well... 6GB would certainly be MUCH better for me than the 3GB I'm stuck with now - but at the price of a new 15" with 6GB I think I'll wait it out until the next update of the MBP's, where at the very elast the 15" will support 8GB - but actually more likely up to 16GB. THAT would be sweet...
  • Reply 3 of 4
    vandilvandil Posts: 187member
    It could also just be heat. Two 4GB modules could run hotter than the unibody can keep cool.

    Also, it could be simply economics: the 6GB ceiling on 15" models could very well be a simple firmware setting to drive consumers to buy the 17" model if they want more RAM.
  • Reply 4 of 4
    I was at MacWorld and personally looked at several 15.4" models with 8GB of RAM. So there goes that theory. Not sure how they did it, but they did.

    Also, it was made very clear that the 15.4" models to be introduced in early spring were going to have the following features; Intel Core i7 processors, options for up to 8GB RAM, 500GB @7200 SATA HD, 750GB @5400 SATA HD, 256GB SSD, 24x dual layer superdrives(Blu-Ray?), 5 megapixil isight webcam supposedly located somewhere in the display screen.

    Another thing that I found very interesting.... there a few people with Sony Vaio laptops running Leopard.... again, I don't know how they did it but somehow they did.
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