Unrecognized RAM in MacBook

[sergio]

I have a MacBook 2 running on 10.4.11. I put two 2 gb RAM bars. The computer recognizes in AboutThisMac the 4gb RAM, but in the activity monitor only recognizes 3gb. I would appreciate any help on how to fix this.  Here are the screen shots. Thanks. Sergio

[AndrewKulin]

Is this a 32-bit vs 64-bit Operating System issue?  I know nothing about Macs, but Windows XP-32 Bit only recognizes up to 3 GB Ram, to get it to see 4GB + you need XP-64.

[Andrew Fee]

It's my understanding that some of the older Intel Macs, up until about two or so revisions ago only had a 32-bit memory controller, which meant they were limited to using ≈3GB RAM. After that, I believe they supported 6GB max, though 4GB was the official limit, and now it's 8GB on the latest machines. (if it weren't for the considerable cost of that 8GB RAM, I'd probably have upgraded at this point)

My MacBook Pro (2.33GHz Core2Duo when that was the top spec) also has this limitation—annoyingly, it was the revision after mine that they got past the 3GB limit.

I think you still get better memory performance from using matched pairs (2x2GB) instead of mixed (2GB + 1GB) but I'm not certain about that.

It's a huge annoyance though, I often end up needing more than 3GB and as notebook hard drive performance is terrible (especially a 2.5 year old one) it's painful when OSX starts paging to disk.

[Jack Flesher]

Older Mac laptop motherboards only recognized 3G ram max...

[schrodingerscat]

It's my understanding that some of the older Intel Macs, up until about two or so revisions ago only had a 32-bit memory controller, which meant they were limited to using ≈3GB RAM. After that, I believe they supported 6GB max, though 4GB was the official limit, and now it's 8GB on the latest machines. (if it weren't for the considerable cost of that 8GB RAM, I'd probably have upgraded at this point)

My MacBook Pro (2.33GHz Core2Duo when that was the top spec) also has this limitation—annoyingly, it was the revision after mine that they got past the 3GB limit.

I think you still get better memory performance from using matched pairs (2x2GB) instead of mixed (2GB + 1GB) but I'm not certain about that.

It's a huge annoyance though, I often end up needing more than 3GB and as notebook hard drive performance is terrible (especially a 2.5 year old one) it's painful when OSX starts paging to disk.

All computers have RAM limitations, something to consider at time of purchase. And you're right, matched pairs of sticks will give better performance, but it will not overcome the limitation of the motherboard.

As to the HDD, replacing it with a 7,200RPM drive will improve Photoshop, etc., performance.

Insofar as PS is concerned, it is recommended to use a dedicated fast scratch disc with no OS installed. A dedicated partition will work, but a separate drive is much better. With a notebook, this means an external drive. Preferably firewire.