Hi,

I have an early-ish (late 2008 or early 2009) aluminum 24" iMac, and I have found out (by trial and error) that the maximum amount of RAM that can be used is 6GB. There are two SO-DIMM RAM slots, so if you use a 4GB stick (I have this in Bank 0) and a 2GB stick. I think you lose dual channel function, but this has a negligible effect on speed.

The really curious thing is that the machine will boot and does "see" two 4GB sticks, but it actually addresses 6GB. If I only used OSX, then having two 4GB sticks would probably be fine, but I also use VMware Fusion and WinXP, and the moment you boot WinXP, the entire machine slows to an excruciating crawl...

I had two 2GB sticks and when I ran Fusion/WinXP things slowed down quite a bit if I used more than one program on the OSX side. Now that I have 6GB, large SketchUp files load much more quickly, and having 3GB for WinXP and 3GB for OSX at the same time makes the machine much more responsive.

Is it an ATI or nVidia equipped model?

Sorry -- it is an ATi model.

Hi Neil, if you PM me the serial code, I can find out exactly what the machine supports, and other details that may prove to be useful in figuring out the problem.

It has been suggested to me that its most likely "Windows XP" in that setup that is causing the problem, as VMware Fusion doesnt usually have that issue otherwise, although Apple have had some very strange setups in terms of hardware support over the years, and it is possible that the machine does not "officially" support 8GB of RAM and that may be the root cause of the issue.

But the serial code is the key to the answer I have been told, please PM it, rather than posting it.


Andy

Thanks Andy,

Another clue is that when I used a version of MemTest, which required booting to single user mode, the maximum that it could work with was ~6GB; even though it "saw" all the RAM. Also, it could not lock the RAM, so the tests took a lot longer?

Officially your chipset only supports 4GB. In reality it can address up to 8GB, but every single device shares that address space, resulting in the 6GB you see.

The downside of forking out for a Mac: You get last generation hardware at a next generation price.

My 24" iMac is a little over 2 years old, and the new iMacs support up to 16GB of DDR3 RAM. I think they are very close to current generation hardware, and the prices have gotten lower. If you price out a Win7 system with a 27" 2560-by-1440 LED backlit IPS monitor, I think you'll see the prices are fairly competitive. And iMac are very quiet, indeed.

Current Macs are somewhat closer to the current generation hardware, yes. Your iMac, however, is running four year old components.


I disagree. A current model iMac starts at £1429 for 27". Take the monitor off and you're still left with at least £900. I can build a superior machine for that money, and it'll have a warranty too.

Let's not go this route, though. Not a lot of point.

The Core 2 Duo was the standard top of the line two years ago. And I don't have to fight with Windows (much).

And the chipset it's sitting on is from 2007. And don't get me started on the deficiencies of OS X..