Should I RAM one slot, or two? Huh huh.

July 13, 2005 12:47 PM

I'm thinking about buying a new iMac G5, and I'd like to bump the RAM up to 1GB from the standard 512MB. The Apple customization menu gives you the option of getting 1GB in two DIMMs or one; the latter is $50 more expensive. Is there any performance benefit in having all the RAM in one place, or is it just a question of keeping a slot open?
posted by logovisual to computers & internet (14 comments total)

Just a question of having a slot open. Actually, 2 matched DIMMs can be faster, because they can be accessed in parallel on some hardware. Not sure whether this applies to the iMac.
posted by trevyn at 12:50 PM on July 13, 2005

one piece of advice i can give is this. buy RAM aftermarket! you will save a butt-load of cash. apple is really high for RAM.
now for your question...performace wise its about the same. so if you are just the casual user, keep it stock and just buy a 512 aftermarket. best of luck.
posted by ShawnString at 12:52 PM on July 13, 2005

paralell doesnt matter for the iMac G5, now for the Power Mac G5, thats a diffrent matter...
posted by ShawnString at 12:53 PM on July 13, 2005

I just got a 20-inch last month and boy, does it rock. I bought a 1 gb stick from Crucial for much less than Apple was charging. It's really easy to install yourself, too. Apple Support has step-by-step instructions on their site.
posted by dual_action at 1:08 PM on July 13, 2005

Second ShawnString. Never buy memory from Apple.

Steve's gots to pay for all those black turtlenecks somehow.
posted by docgonzo at 1:11 PM on July 13, 2005

If you have two separate sticks that are both the same size, the iMac switches to a special mode where it reads from both of them at the same time, which in theory works faster, but benchmarks have shown it making no difference whatsoever.

The reason that Apple charges more for a single stick is that:
a) A 1GB stick has to use chips that are twice as dense as those on each 512MB stick. But each of these chips actually costs more than twice as much to make.
b) It leaves the second slot free for upgrading later, which may be a consideration.

I'd buy it with 512MB and add a 512MB stick from Crucial.
posted by cillit bang at 1:26 PM on July 13, 2005

But each of these chips actually costs more than twice as much to make.

Unlikely. The chips for the 1GB stick will only be twice as expensive if they are twice as large as the chips for the 512MB stick. New generations of memory are usually made with smaller and smaller "wires", so it is more likely that the chips cost exactly the same. More importantly, most machines have very few memory slots, so users are willing to pay MORE for higher density sticks. The manufacturer charges more for these because they can and to pay for the new fabrication gear required to make the higher density chips.

In the worst case, the chips will cost exactly twice as much. More likely, they will cost slightly less than 2x as much, or about the same as the old chips. Memory makers have repeatedly the subject of anti-trust investigation. The chips are cheap and profitable to make.

The slightly less obvious conclusion is that you should only buy as much computer as you need now, or for the next six months. Within a year or two, you will be able to buy CPUs that are twice as powerful and memory that is half as expensive. If it is cheap to get two 512 MB sticks now, go for it. You will throw them both out in a few years when you upgrade to 4GB, unless you are throwing out the whole iMac.
posted by b1tr0t at 1:58 PM on July 13, 2005

Crucial has often been recommended in previous memory-related questions.
posted by kirkaracha at 2:34 PM on July 13, 2005

OWC is also good for Mac RAM. Crucial can be overpriced, sometimes dramatically. You might be able to get even cheaper without problems if you go even more generic, but everything from OWC has been rock-solid for me, and they know Macs.
posted by trevyn at 3:57 PM on July 13, 2005

And dealram is good for finding those generics that have been tested in your Mac.
posted by trevyn at 4:00 PM on July 13, 2005

(b1trot, I'm aware of the economics of chip manufacturing, I was just using "cost to make" as shorthand for "cost to buy from a manufacturer", which in practical terms is the same thing)
posted by cillit bang at 6:02 PM on July 13, 2005

From recent personal experience, and to echo sentiments above, buy the stock iMac with 512, and the money you would save not buying the extra RAM from Apple will almost buy you a 1GB stick aftermarket! I did this, and am v.happy. 512 is just never enough with all the Mac OS X oompa-loompas doing on 'behind the scenes' (Spotlight, Dashboard, etc etc)
posted by DannyUKNYC at 11:00 PM on July 13, 2005

I bought my iMac G5 (1.8Ghz 17") with the factory 256 megs, then just bought two 512M sticks from CompUSA (because I was impatient; I paid $99/stick versus the $50/stick I could have gotten it for mailorder). Even with the CompUSA markup it was STILL cheaper than buying the RAM from Apple.

Took the 256M stick out and gave it to a friend.
posted by mrbill at 11:42 PM on July 13, 2005

Buy as little RAM from Apple as possible. Apple charges any where between double and five times actual retail cost. Sometimes even more!
posted by blasdelf at 2:47 AM on July 14, 2005