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2GB or 2.5GB... Does dual channel matter?

S

Samwise592

macrumors regular
Original poster
Feb 4, 2007
163
0
Long Island, NY
So I've got a choice to make... with Leo arriving at my door in under 24 hours, i realized that I'm gonna need 2gb of ram to make it preform like it should, but now I've got a choice:

1.) Buy a 2gb stick and replace one of my 512 sticks for a total of 2.5GB (Not dual channel)
2.) Buy a 2gb kit (2x1gb) and run dual channel....

which one will give me better performance?
 
It all depends on how much RAM you need. If you almost never exceed 2GB in use, dual-channel is marginally faster.

If you exceed 2GB of memory needed, non-dual-channel RAM is overwhelmingly faster than virtual memory disk swapping.
 
iMac C2D RAM question

Ok, so here's a question I've been pondering: the iMac C2D (pre-aluminum models) can theoretically have 2 x 2GB modules inserted but will only really use 3.3GB of the RAM (approx. 700 MB will be "lost" due to hardware limitations).

So, question is, what is better....to have 2 x 2GB modules installed and lose the 700MB but have dual-channel support (if it will even support it on this configuration) or to just have the 1 x 2BG, 1 x 1GB setup for a total of 3GB (max) and mis-matched pairs without dual-channel?
 
twoodcc said:
ok. you just have to do it yourself?

what happens if you try 4GB?
Click to expand...
Yes, it's aftermarket only.

On the 4 GB front, it'll either say there's 4 GB but only be able to use 3-3.25 GB or it just won't boot at all.

bigus7674 said:
Ok, so here's a question I've been pondering: the iMac C2D (pre-aluminum models) can theoretically have 2 x 2GB modules inserted but will only really use 3.3GB of the RAM (approx. 700 MB will be "lost" due to hardware limitations).

So, question is, what is better....to have 2 x 2GB modules installed and lose the 700MB but have dual-channel support (if it will even support it on this configuration) or to just have the 1 x 2BG, 1 x 1GB setup for a total of 3GB (max) and mis-matched pairs without dual-channel?
Click to expand...
Just go with the 3 GB.
 
bigus7674 said:
Ok, so here's a question I've been pondering: the iMac C2D (pre-aluminum models) can theoretically have 2 x 2GB modules inserted but will only really use 3.3GB of the RAM (approx. 700 MB will be "lost" due to hardware limitations).

So, question is, what is better....to have 2 x 2GB modules installed and lose the 700MB but have dual-channel support (if it will even support it on this configuration) or to just have the 1 x 2BG, 1 x 1GB setup for a total of 3GB (max) and mis-matched pairs without dual-channel?
Click to expand...

Of course the dual channel, but it costs more.
 
killerrobot said:
Buy the kit 2X1 kit.
Yes, running dual channel makes a big difference.
Click to expand...

It's marginal.

twoodcc said:
can you put a 2GB stick in a macbook?
Click to expand...

You can put two in, it's just not worth it.

flopticalcube said:
http://guides.macrumors.com/Understanding_Intel_Mac_RAM

Dual channel is 5-8% speed improvement. Generally more RAM is better.
Click to expand...

I use 2.5GB RAM in my MB C2D 2.16

twoodcc said:
ok. you just have to do it yourself?

what happens if you try 4GB?
Click to expand...

It only addresses 3.3GB and if you address more than 3.3GB, or you are hitting the limit, you face instability. Kernel panics etc...
 
Eidorian said:
Eh?

The memory addressing isn't a software issue.
Click to expand...

There was a thread on here, a forum user put 2 x 2GB sticks in a MB and said that it saw 4GB. Everyone asked questions and the end result was when the computer used as much RAM as possible it became unstable because it hit the limit and threw a wobbly.

Use search to find it, I have no idea where it is now, but it's here... somewhere.
 
so... since that got totally off topic...

will my performance be better with 2gb of dual channel, or 2.5gb with mismatched ram?

...Before you ask, i normally have Firefox(4-10 tabs), iTunes, iChat, transmission, a few finder windows, and sometimes MS word open. (a few dashboard widgets as well)
 
Samwise592 said:
so... since that got totally off topic...

will my performance be better with 2gb of dual channel, or 2.5gb with mismatched ram?

...Before you ask, i normally have Firefox(4-10 tabs), iTunes, iChat, transmission, a few finder windows, and sometimes MS word open. (a few dashboard widgets as well)
Click to expand...
You'll be better off with more RAM.

samh004 said:
There was a thread on here, a forum user put 2 x 2GB sticks in a MB and said that it saw 4GB. Everyone asked questions and the end result was when the computer used as much RAM as possible it became unstable because it hit the limit and threw a wobbly.

Use search to find it, I have no idea where it is now, but it's here... somewhere.
Click to expand...
I remember quite a few threads like that but I don't remember the instability being software based.
 
Samwise592 said:
so... since that got totally off topic...

will my performance be better with 2gb of dual channel, or 2.5gb with mismatched ram?

...Before you ask, i normally have Firefox(4-10 tabs), iTunes, iChat, transmission, a few finder windows, and sometimes MS word open. (a few dashboard widgets as well)
Click to expand...

If you are not using all of the 2G than 2X1 will be faster.

Eidorian said:
You'll be better off with more RAM.
Click to expand...

LOL! Nice to see two opposite answers to the same question! Now I hope that settled it for you. :D
 
Eidorian said:
You'll be better off with more RAM.
Click to expand...

I was/am in exactly the same situation. I have a 2GB module and a 512MB module and I couldn't be happier, they both run at the same temperatures and it's smoother than when it was just 1GB matched.

I remember quite a few threads like that but I don't remember the instability being software based.
Click to expand...

I never said it was software based, but I can see how you'd get that conclusion, all I said was that it had instabilities and kernel panics. For all I know that could be paranormally based :p

I'm just repeating what I read in the thread. Now I'm going to bed. :p
 
samh004 said:
I was/am in exactly the same situation. I have a 2GB module and a 512MB module and I couldn't be happier, they both run at the same temperatures and it's smoother than when it was just 1GB matched.
Click to expand...
Same situation back on my iMac G5. I'm glad I had 1.5 GB instead of 1 GB.


samh004 said:
I never said it was software based, but I can see how you'd get that conclusion, all I said was that it had instabilities and kernel panics. For all I know that could be paranormally based :p

I'm just repeating what I read in the thread. Now I'm going to bed. :p
Click to expand...
I blame solar flares.
 
Eidorian said:
I noticed that.

Even Barefeats admits you're better off going with more RAM then strictly with dual channel.

I can get the links if you want.
Click to expand...

It really depends if the OP is even going to reach the 2GBs with his current use. I think the bump from 2 to 2.5 is not a whole lot. If you are going to start swapping at 2, then you probably will be at 2.5 as well.

Samwise592: check to see how much blue and green is left in Activity Monitor.
 
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