Late 2008 unibody MacBook Pro + 6GB RAM + Snow Leopard = Kernel Panic

The Late 2008 MacBook Pro is officially limited to 4GB. If you go to the apple store under Mac Accessories, select memory, and select 15" MacBook Pro with 2.8GHz RAM then you will get a listing for an 8MB RAM upgrade. HOWEVER, I contacted the store, and they looked up based on my MBP serial number (Late 200*), and was told that 4GB is my maximum.

So, why the kernel panics with 6GB? Well, maybe it's the mismatched modules. The MBP supports dual-channel memory, but dual-channel access only works with matched pairs. Maybe Snow Leopard is more aggressive about going for dual channel memory access.

Or, maybe Apple put something in arbitrarily to limit those systems to 4GB max once they found out that people were going beyond the officially supported amount. That wouldn't be out of character, given the way the company enforces its dictates (ask Palm Pre owners about that).

Either way, it looks like we're stuck at 4GB, which sounds like a lot until you try to run multiple VMs simultaneously.


<edit: I guess it's worth asking: have people had this problem in 10.6.1, or just in the original 10.6 release?>

Message was edited by: DelegatorNH

Apple doesn't arbitrarily limit RAM for no good reason; there must be a system limitation somewhere that limits usable RAM on those systems.

Remember it's not just the CPU, it's all the ancillary board support chips as well as the way the board is designed that are limiting factors as well.

This is actually an error in the Apple Store web site, as current 2.8 GHz 15" MBPs (introduced mid-2009) are capable of using 8 GB of RAM; late 2008 2.8 GHz 15" MBPs are only capable of using 4 GB.

In fact, if you click on the entry for "MacBook Pro 17-inch, 15-inch 2.0 - 2.6 Ghz" you will find an entry for your older 2.8 GHz 15" MBP stating there are no memory upgrades currently available for it.

Could this be because the ram modules are not a pair? Would two paired 4gig modules work?

I was wondering the same thing...

My new mid-2009 15" MBP Manual says in regards to memory: You can add two 4 GB memory modules for a maximum of 8 GB of memory. For best performance, fill both memory slots and install an identical memory module in each slot.

The original poster has a late 2008 MBP, which only accepts a maximum of 4 GB of RAM.

The new mid-2009 MBP accepts a maximum of 8 GB of RAM.

Two different machines.

And there was I thinking a 64 bit operating systems would open the door to allowing HUGE amounts of RAM to be installed & used...

Ive read in many locations that 64 bit OS should have at least 4Gig RAM to ensure good performance!

I think ill hold off 10.6 upgrade till all this has been fixed... i really dont want my MBP to die in front of 400+ party goers while im Djing

{quote:title=William Kucharski wrote:}
Apple doesn't arbitrarily limit RAM for no good reason; there must be a system limitation somewhere that limits usable RAM on those systems.
{quote}

Maybe "arbitrarily" was too strong a word, but the fact is that many people were able to use 6GB RAM on the late 2008 MBP. And, this seems to have changed with Snow Leopard, which indicates that there was a change in the OS -- either intentional or not -- that has caused that model of MBP to stop working with more than 4GB RAM.

I think everybody acknowledges that people using 6GB RAM in mismatched 2/4 GB modules were not in an officially supported configuration. But, it's a shame that what was supposed to be an upgrade turned out to be a step backward in one major regard. If anything, I'd have liked to see Snow Leopard add official support for 6GB RAM instead of making this amount unusable.

DelegatorNH wrote:
I think everybody acknowledges that people using 6GB RAM in mismatched 2/4 GB modules were not in an officially supported configuration. But, it's a shame that what was supposed to be an upgrade turned out to be a step backward in one major regard. If anything, I'd have liked to see Snow Leopard add official support for 6GB RAM instead of making this amount unusable.

Not if there are other reasons why 6 GB makes for an unusable configuration on that machine.

Remember that even if System Profiler reported 6 GB was installed, that doesn't mean all 6 GB was usable, nor that there would not have been other issues with doing so.

This has nothing to do with Snow Leopard per se, though SL apparently now panics when an amount of RAM in excess of that supported is installed.

Once again, it's not actually a step "backwards" if exceeding the maximum amount of supported RAM caused other issues which you, personally, may not have run into.

Maximum amounts of installed RAM are not, in general, an OS issue, they're a hardware support limitation.

I am not sure if I am hearing this right. But unibody late 2008 have 4GB as a maximum amount of RAM that can be installed. Yes core 2 duo is 64bit processor. Yes Snow leopard is 64 Bit processor but the memory controller may limit the amount of RAM that can be installed


http://manuals.info.apple.com/enUS/MacBook_Pro_15inchLate2008.pdf

"You can add two 2 GB memory modules for a maximum of 4 GB of memory. For best performance, fill both memory slots and install an identical memory module in each slot."


They have not updated it to 6GB not that I know of.

Message was edited by: kisuke3

There are a variety of things that can limit the amount of RAM that can be reliably used by a system, most of them having to do with limitations of hardware components or of the mainboard itself - not necessarily just the memory controller.

Just as a hypothetical example, say the memory controller can handle a 64-bit RAM address but the video or disk controller for whatever reason cannot.

Rather than slow down the OS by forcing it to do I/O through bounce buffers it may be easier just to limit the maximum supported RAM in such products to 4 GB.

As I said - completely hypothetical, just an example.

I meant to reply to the thread starter but I agree with you William 🙂 just my two cents worth, i just think its his 6GB ram that may be causing this. I've installed SL onto 5 machines at least. Family and friends and have no issues or whatsover

Cheers!

No problem.

It is his 6 GB of RAM that is causing this issue as it's an unsupported, untested configuration for his machine.

Like I said in my first post its undocumented in the specs page of apple.com/support and it clearly said 4GB as the maximum. I'm glad we are on the same boat. Cheers mate enjoy the weekend

Those of you who were able to successfully upgrade to 6 GB in 10.5 Leopard: Would you mind telling me which manufacturer provided your 4 GB RAM module? I'm asking because I ordered a 4 GB RAM Stick from OWC and received a Hynix module, which isn't working (uMB 2.4 GHz). The Nvidia website lists compatible RAM for the 9400M chipset and the only 4 GB module listed is a Micron (Crucial) part. Other users have reported being able to upgrade their uMBP (late '08) 2.53 GHz in 64-bit kernel mode with SL and their module IDs were 0x029E.

Hi Guys

I have the same problem like everyone else. My first kit game me all the errors and the second I received worked fine until I rushed the system. So I called OWC (Macsales.com) to get a refund but I also sent them this topic and told them that I would LOVE them to find a solution. Here is the answer I got few seconds ago:

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Thank You for that information. I we have solved these issues. We have found that the Hynix brand memory was the culprit and that samsung memory works fine. That is why I suggested another replacement with a Samsung brand. I have passed along the message to management. If you have any other questions please don't hesitate to ask!

Brittany Finn
Customer Service
Other World Computing, Inc.

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I will go ahead and ask for that Samsung Kit and cross my fingers. If it works, I will let you guys know.

Thanks for sharing this problem.