4Gb Ram is it worth?

jota73

macrumors 6502
Original poster
Apr 19, 2006
301
0
South America
I am about to order my 20" 2.4GHz iMac, and wanted to upgrade its RAM, I have read that having 4 GB RAM the total usable memory would be 3.3GB.

In other words.

Is it worth buying 2Dims of 2GB each to sum up 4GB when the usable would be 3GB or just buy 1 Dimm of 2g to sum up 3Gb, so that the total 3GB would be usable?

My post is based on what I read here
 

superleccy

macrumors 6502a
Oct 31, 2004
978
22
That there big London
* The maximum RAM is different for different logic boards:

1. Core 2 Duo Santa Rosa machines, (MacBook Pros and the new iMacs) can recognize a full 4 GB of RAM.
2. Earlier Core 2 Duo machines can recognize a potential 3.3 GB (with 2 x 2 GB installed... the top 700 MB is wasted, so the practical maximum is 3 Gb with 1 x 1 Gb and 1 x 2 Gb). This is a hardware limitation.
* With 4 GB installed, these machines will report 4 GB in System Profiler, but the operating system will only use 3.3 GB.
I believe that the new 2.4GHz iMacs have the Santa Rosa chipset (that's what the article seems to say anyway). Therefore, the first point would apply, and your new iMac would be able to "recognise a full 4GB of RAM".

SL
 

jota73

macrumors 6502
Original poster
Apr 19, 2006
301
0
South America
I believe that the new 2.4GHz iMacs have the Santa Rosa chipset (that's what the article seems to say anyway). Therefore, the first point would apply, and your new iMac would be able to "recognise a full 4GB of RAM".
SL

R U totally sure?
 

je1ani

macrumors 6502
Sep 19, 2007
455
1
You're confusing the old white iMac C2Ds with the new Aluminum C2Ds with SR chipsets
 

superleccy

macrumors 6502a
Oct 31, 2004
978
22
That there big London
R U totally sure?
Yes. But don't sue me.
not according to the text posted at Guides...in macrumors
Read it again.

Consider also the following which I believe to be facts:
  • The Core 2 Duo 2.4GHz processors are Santa Rosa-only.
  • The previous generation of Core 2 Duo iMacs (non-Santa Rosa, maxed out at 2.33GHz) would only ship with a maximum of 3Gb RAM.
Also, you get better performance if your DIMM modules are of equal size, becuase they work in dual-channel mode (or something).

But again, don't sue me.

SL
 

Sun Baked

macrumors G5
May 19, 2002
14,874
57
You're confusing the old white iMac C2Ds with the new Aluminum C2Ds with SR chipsets
Yep, the Napa chipset had the hardware DMA reside within the 4GB memory, and Santa Rosa chipset tossed it outside that. So the al-iMac is the full 4GB of memory.

Of course the max memory is awaiting the 4GB SO-DIMM test.
 

Similar threads

  • ivanjay205
15
Replies
15
Views
920
  • firelighter487
6
Replies
6
Views
546
  • techmeoutbaby
62
Replies
62
Views
7K
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.