Last Gen White iMac - Still limited to 3GB?

[sigamy]

Just wanted to put a final nail in the coffin on this...I currently have two 1gb modules in my 20" 2.16Ghz C2D iMac (the last white iMacs).

From what I've read, if I add two 2gb modules, the system will only be able to access 3gb. Is this still correct?

If it is correct, should I just install one 2gb module + one 1GB for a total of 3gb? Or should I go with matching pairs and install two 2gbs? How much of a speed difference will there be?

 

[roland.g]

3GB is better performance than 2GB matched. The matched vs. unmatched doesn't matter as much as the total amount. Actually you will get 3.2 if you put in 4GB b/c that is all the chipset can address. It wasn't until the Santa Rosa chipset that 4GB was available. 3 would be your best bet. Don't worry about putting in 4. You could also stay with 2 if you wanted and be fine.

 

[neiltc13]

Not really sure where this sudden desire for everyone to have 4GB RAM comes from. I use 2GB and find that even this is excessive.

 

[eXan]

Not really sure where this sudden desire for everyone to have 4GB RAM comes from. I use 2GB and find that even this is excessive.

Me too

It seems like everyone at macrumors is getting 4 GBs installed in their MacBooks and iMacs. What for?

I barely hit the 1 GB limit on my MacBook doing web/mail/chat/itunes/pages/word + h.264encoding and my Page Outs rarely exceed 200-300 MBs.

iMac G5 has 1.5 GBs and I'm using Aperture on it with Photoshop to edit 8 MP photos, but its more limited by its slow CPU than amount of RAM (I checked Activity Monitor while doing doing my usual stuff in those 2 apps and RAM was just almost filled)

 

[OllyW]

2GB RAM chips have dropped in price recently, on Crucial UK last week they were only £10 more expensive than 1GB so they are no longer an expensive option.

I've got 4GB in my mini, only accessing 3.3GB but with the slight advantages of dual channel memory (which works better with graphics that use shared RAM).

More info here.

 

[Leon Kowalski]

... my Page Outs rarely exceed 200-300 MBs.

1) The OS-X filesystem uses all available "idle" memory for disk buffer-cache.
This can greatly improve the performance of many apps by avoiding Page Ins
when re-reading "disk data" that's already resident in "inactive" RAM. Thus,
adding memory does improve performance -- even when there's more than
enough to prevent Page Outs.

2) Independent of Page In/Page Out considerations, a "matched pair" of memory
modules yields a 5%-ish improvement in overall performance. So, "wasting" $50
or so for a second 2GB module is a huge bargain -- compared to "investing" $250
in a 2.4 GHz to 2.8 GHz CPU upgrade (which yields only a 10%-ish improvement
in overall performance).

LK

 

[gorby]

You will still get better performance from 4GB matched in a white iMac.

Look at the benchmarks from OWC: http://eshop.macsales.com/shop/Memory_Benchmark/Apple_iMac/

Although the first Core 2 Duo iMacs support only up to 3.0GB, by popular demand did also test these with 4.0GB, where a some performance benefit is present due to the then enabled 128 Bit Memory addressing.