Upgrade RAM: 1X4GB or 2X2GB

Computer people here’s a softball for you:

I’ve got a late 2008 MacBook (5,1) that, other than having to replace the battery earlier this year, still runs perfectly and does everything I need it to do. It still has the original 2X1GB RAM, which is still sufficient for most applications I run (I experience some degree of slowdown and “pinwheeling” when I have a lot of stuff open), but I’m planning on upgrading to Mountain Lion and would like to upgrade my RAM for improved performance.

I’m pretty sure I know the answer, but just to double-check, do I want 1 4GB stick, or 2 2GB sticks?

Bonus question: Apple’s official documentation says this computer can use up to 4GB of RAM. Why can’t I put in more?

The 4 GB limit is probably related to 32-bit addressing limitations. If there’s a 4 GB chip that could be used in your laptop, then it’s clearly not a hardware limit.

I have too much trouble these days finding the tech specs on Apple computers* to try to find out if your laptop is 64-bit capable. If it is, then you should be able to support more than 4 GB under a 64-bit operating system.

  • At least back in the days of the Performa 61XX days, you had a real model number you could remember and look up to confirm how crappy your computer was. Now, you have a much better computer, but you have to remember either a serial number (in tiny print on the back) or some combination of cats, release dates and construction materials.

I don’t know the Mac OS very well, but with PCs a 32-bit based OS could not address memory above a certain threshold (was it 3+?). Can you check the About this Mac (or similar) and see if both hardware and software are 64-bit? If not, that might be where the limitation comes from. Crucial.com is a great source of info in that way too–maybe you could scan then talk on one of their ‘chat’ lines (which would also give you a definitive answer to the 1x or 2x question–I thought they worked best in pairs, but they’ll be the right people to ask. Oh, and Dracillix).

The limitation on addressable memory is one of hardware - CPU mainly, and software - the Os needs to be 64 bit.

Your PC manual, however, is probably talking about a physical limit on the type and number of RAM modules supported by your motherboard.

In other words, it likely only has 2 RAM slots, and each slot only supports up to 2GB modules.

Also, you want to fill both modules. The north bridge probably uses a dual channel memory architecture which will perform better when both channels are filled.

So 2x 2 GB sticks is what you want.

Not much of an Apple Guy but I would assume apple uses the same types of multi channel architechture on its boards.

This would generally give you a small boost in performance having 2x2GB vs a single 4GB module.

No, I meant “Dracillix,” a dubstep computer designer.

(sorry about the spelling)

Quibble: many machines for the last couple years have integrated the northbridge functions onto the CPU die (AMD fusion series, Intel Sandy Bridge)

That’s what I thought.

Thanks for the info, all.

And it is an Intel “Core 2 Duo” running OS X Lion, which are both 64-bit, with 2 RAM slots.

Yes, but that’s probably not the architecture in a 2008 mac book.

Go to the Apple Menu, Select “About This Mac” then click “More Info”. This will give 99% of all Mac users all the info they need to identify their computer specs, and purchase upgrades from OWC.

If you click on “System Report”, the second line, “Model Identifier” will give the Model number you are looking for (MacPro 3,1 in my case, aka, the “Early 2008 Mac Pro”)

Get 2x2GB if you NEVER plan on upgrading again. However, if you think you might want 8GB of RAM (and, with prices as low as they are, I’d do it now), go with the 1x4s.

from here.

I’ll second Beowulf on this one and recommend a single 4GB stick. I’d rather pay for two 4GB sticks (one now, one later), than two 2GB sticks now and two 4GB sticks later.

You do get slightly better performance with multiple memory sticks, but not enough to be worth the higher end price, in my opinion.

If it CAN support 8 gigs of RAM I’d go ahead and get them. 8 Gigs should be cheap anyway. But yeah, in that case going single channel 4 GB if for some reason two modules isn’t an option financially should be fine.

Apparently, with some kind of "secret firmware, you can use up to 8 GB of RAM in that model. I’m surprised that it is officially limited to 4GB. Everything I can find online says the MacBook Pro 5,1 supports up to 6GB RAM (4GB + 2GB) normally, and 8GB with this firmware. You can follow the flowchart to see if it will work for you.

If I have the computer in front of me, then there’s no problem. It’s just a matter of remembering the models myself or interpreting what other people say. For example, my family history of Macs is: Mac Plus, LC II, PowerBook 180, PowerMac 6100, PowerMac 7100, PowerMac G3 (Blue & White). After that, I really can’t remember them. I had a: PowerBook G4 (with some kind of metal exterior), iBook G4 (with white plastic exterior), iMac (first Intel version), iMac (first aluminum version). You can see that I remember the computer I had 20 years ago better than I remember the model of the one I have right now.