RAM for iMac G5 (new iMac owners' input greatly appreciated)

Elan0204

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Apr 16, 2002
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So my new iMac is on the way with 1 512MB DIMM from Apple, but I'm thinking of adding another 512MB DIMM so I can have an even 1GB and dual channel. Can anyone who has the new iMac tell if the CAS latency needs to match for the memory to run in dual channel mode?

Also, I was looking at the following RAM:

Manufacturer: Corsair <---Corsair Value Select, if that makes a difference
Speed: DDR400(PC3200)
Type: 184 Pin DDR SDRAM
Error Checking: Non-ECC
Registered/Unbuffered: Unbuffered
Cas Latency: 2.5
Support Voltage: 2.5V
Bandwidth: 3.2GB/s
Organization: 64M x 64 -Bit
Warranty: Lifetime

This will work in the new iMac, right? Anyone have any experience with this RAM? Will it run duak channel with the RAM I get from Apple?

I know most people recommend Crucial, but this is $12 cheaper and has a lower CAS latency, so I'm looking for reasons why I should not go with this RAM.
 

Datazoid

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May 10, 2002
167
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Elan0204 said:
Also, I was looking at the following RAM:

Manufacturer: Corsair <---Corsair Value Select, if that makes a difference
Corsair does not support Macs. If the chip goes bad on you, you are SOL. This is detailed on their web forums. I bought one of their chips once for my eMac, and it turned out to be faulty...thankfully within the time frame that Fry's allowed for returns. That is reason enough for me. For $12 dollars, get the better quality, warranty, and support of Crucial.
 

rdowns

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Jul 11, 2003
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Elan0204 said:
So my new iMac is on the way with 1 512MB DIMM from Apple, but I'm thinking of adding another 512MB DIMM so I can have an even 1GB and dual channel. Can anyone who has the new iMac tell if the CAS latency needs to match for the memory to run in dual channel mode?

Also, I was looking at the following RAM:

Manufacturer: Corsair <---Corsair Value Select, if that makes a difference
Speed: DDR400(PC3200)
Type: 184 Pin DDR SDRAM
Error Checking: Non-ECC
Registered/Unbuffered: Unbuffered
Cas Latency: 2.5
Support Voltage: 2.5V
Bandwidth: 3.2GB/s
Organization: 64M x 64 -Bit
Warranty: Lifetime

This will work in the new iMac, right? Anyone have any experience with this RAM? Will it run duak channel with the RAM I get from Apple?

I know most people recommend Crucial, but this is $12 cheaper and has a lower CAS latency, so I'm looking for reasons why I should not go with this RAM.
Someone already posted their new iMac has a CAS 3 DIMM in it. Based on that, I ordered a Crucial 512MB DIMM, same specs from newegg.com. They were cheaper than crucial.
 

Elan0204

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Datazoid said:
Corsair does not support Macs. If the chip goes bad on you, you are SOL.
That doesn't sound good. Although, RAM is RAM, so couldn't you just say you were using it in a PC and it no longer works? However, maybe I don't want to do business with a company that has such narrow-minded policies.

rdowns said:
Someone already posted their new iMac has a CAS 3 DIMM in it.
So the 2 chips must have the same CAS latency for dual channel? The 2.5 Corsair chip wouldn't adjust to be a little slower to match the 3 of the Apple chip?

edit: rdowns, your avatar makes me think you might enjoy this from the iTMS. :D
 

rdowns

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Jul 11, 2003
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Elan0204 said:
That doesn't sound good. Although, RAM is RAM, so couldn't you just say you were using it in a PC and it no longer works? However, maybe I don't want to do business that has such narrow-minded policies.



So the 2 chips must have the same CAS latency for dual channel? The 2.5 Corsair chip wouldn't adjust to be a little slower to match the 3 of the Apple chip?

edit: rdowns, your avatar makes me think you might enjoy this from the iTMS. :D
That's how I understood it. Seems to me that a matched pair would include CAS too.

Thanks, but I prefer the INXS version.
 

ToddW

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Feb 26, 2004
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i'm using corsair in mine, and it is working beautifully. no problems here.
 

Elan0204

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If I buy Crucial memory from Newegg as recommended, how does the warranty exchange process work? Is Crucial really good about their lifetime warranty even if you don't buy the RAM from them directly (especially since the chip from Newegg is OEM, not retail)? If anyone has ever exchanged a RAM stick with Crucial, how does the process work exactly?
 

tateusmaximus

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Sep 9, 2004
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for dual channel i believe you will need two matched sticks. i thought only from the factory can they be matched.

thats why im not oredering ram from apple (other than they are pretty expensive for 2gig) but so that i can get two matched gig sticks.

could be wrong though
 

aswitcher

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Oct 8, 2003
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tateusmaximus said:
for dual channel i believe you will need two matched sticks. i thought only from the factory can they be matched.

thats why im not oredering ram from apple (other than they are pretty expensive for 2gig) but so that i can get two matched gig sticks.

could be wrong though
Whoa, thats not a cheap option...going to be a nice machine.
 

Elan0204

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Is dual channel that picky that the RAM has to be from the same manufacturar too? You would think number of MBs and CAS latency would be more enough, if not more than enough.

How can you tell if the RAM you put in is running dual channel?

edit: This is the correct RAM for the iMac G5, right? There price is better than NewEgg's, and they offer free 2 day shipping. They're better reviewed than NewEgg too, which I thought was impossible.
 

Elan0204

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This is from the first link posted in the "iMac G5 not so quiet" tread. Here is the link, but I'll put the contents below.

Matched RAM Reader Doug Eldred also sent us the following question: "Does anyone have any actual data for how much difference 'matched RAM' makes on the G5 iMac? Is this a mostly theoretical boost, or does it really provide a user-noticeable improvement?"

Doug is referring to Apple's documentation stating that:

"If only one DIMM is installed, the memory bus is 64-bit. If two non-identical DIMMs are installed, there are two 64–bit memory buses. If two identical DIMMs are installed, the memory bus is 128-bit. Identical DIMM pairs have the same size and composition and provide the fastest and most efficient throughput."

Although we haven't yet received any real-world reports from readers, the German site PPCNUX provides benchmarks for a 1.8GHz iMac G5 using XBench 1.1.3. Specifically, the benchmarks compare an iMac G5 with two unmatched DIMMs totaling 1.25GB of memory to the same iMac with two matched 512MB DIMMs (for a total of 1GB). Even though the former system had more RAM, the "matched" system returned significantly better results:

System Fill:
Unmatched: 1625.25
Matched: 2231.49

System Copy:
Unmatched: 861.25
Matched: 1041.32

Stream Copy:
Unmatched: 1255.89
Matched: 1615.10

Stream Scale:
Unmatched: 1251.27
Matched: 1657.52

Stream Add:
Unmatched: 1423.78
Matched: 1781.15

Stream Triad:
Unmatched: 1441.01
Matched: 1794.59
Personally, I don't think that xbench is a very good benchmark, but those speed differences are pretty significant.
 

BakedBeans

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Elan0204 said:
This is from the first link posted in the "iMac G5 not so quiet" tread. Here is the link, but I'll put the contents below.



Personally, I don't think that xbench is a very good benchmark, but those speed differences are pretty significant.
that really is stunning....

so i cant believe that is so big an increase from smaller ram... so any iMac buyers... make sure you get this sorted...
 

Jalexster

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Jun 8, 2004
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If I buy an iMac G5, i'll order with the 256 stick, and order a couple of 512 sticks from crucial. This would be the best thing to do, right?
 

BakedBeans

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Jalexster said:
If I buy an iMac G5, i'll order with the 256 stick, and order a couple of 512 sticks from crucial. This would be the best thing to do, right?
no the cheapest way to do it would to be to order 1 chip of 512 at $75 from apple and 1 chip from crucial at $99

saving you 25 bucks over crucial and 50bucks ove apples price :)
 

XIII

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Aug 15, 2004
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But those woudln't be matched would they? Does the "matched" have to be from the same manufacturer, or, just literally 512 is matched with 512. I have decided I want 1gig of RAM in total, what would be the best way to do this then? I understand the cheapest way would be 2 x 512 sticks but do they have to be from the same manufacturer? Basically, my question is this: What do I need to get the benefits of the matching thing, and to have 2 x 512 sticks...?

Thanks :cool:
 

Elan0204

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A cheaper way then AL-FAMOUS's method would be to do one of two things:

Method 1: Spend $75 ($67, if education) to upgrade from 256MB to 512MB from Apple. Then buy a 512MB DIMM from here for $86 with free 2 day air shipping. I ordered from them, and they delivered quiickly as promised. Haven't installed the RAM chip yet, but there should be no problems as the chip was exactly as described. This is the same chip you would get from Crucial directly, only it doesn't come in the retail packaging. It still has a lifetime warranty, though. Total price is $161 ($153, if education).

Method 2: Leave the RAM at 256MB from Apple. Order 2 chips of 512MB from the above link. Sell the 256MB RAM chip and get a little money back. Total price is $172 less whatever you get when you sell the 256MB DIMM.
 

Elan0204

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XIII said:
But those woudln't be matched would they? Does the "matched" have to be from the same manufacturer, or, just literally 512 is matched with 512.
It is unclear at this time what the exact requirements are, but most people seem to believe that you have to match 2 things: the size of the DIMM (i.e. 512MB), and the CAS latency. Apple seems to be shipping RAM with a CAS latency of 3, which matches the memory Crucial sells for the iMac. Additionally, while I'm yet to open my iMac to confirm this, Apple tends to use Crucial memory in its desktops anyway, so you should end up with chips from the same manufacturer anyways. Whether or not the iMac is that picky, about switching to 128 bit mode as to require matching manufacturers, is unknown at this time.
 

XIII

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So as far as we understand at the moment, you will get the increased speed, if you upgrade to 512mb on apples website, and order 512 from crucial... Thanks for your replies ;)
 

Elan0204

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XIII said:
So as far as we understand at the moment, you will get the increased speed, if you upgrade to 512mb on apples website, and order 512 from crucial... Thanks for your replies ;)
XIII, some new information about how exact the chips need to be has come to light. I highly recommend checking out this thread before making your purchasing decision. It looks like you either need to get 1 256MB DIMM from Apple (which you will then sell/put in storage) and 2 512MB DIMMs from Crucial, or order the full 1GB from Apple directly if you want to be sure to get the 128 bit memory bus.
 

plasmadis

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Sep 23, 2004
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I've got 2 sticks of 512 MB Kingston ValueRAM in my iMac G5 20". All I did was make sure it was DDR 400, and CAS 3, and figured I'd be good to go. Only cost me $89 each at a local computer store, reflecting a discount for paying in cash. Try doing that with an online store. :)

I mentioned this in the "iMac G5 Now Shipping" thread, and someone mentioned that in some other thread people said they were having problems with ValueRAM in G5s. I tried searching for this thread, but other than one post from a guy asking "should I get ValueRAM for my G5?", I couldn't find anything.

I've been running mine for about 5 days now, no probs at all.
 

XIII

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Thanks for the update :) Thats a bit of a bugger... It'll cost me more now, and I'll have 256mb sitting around... Ah well...
 

Elan0204

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plasmidis, please run the bus checker from this thread to see if you are running a 64 bit or 128 bit memory bus. I'd imagine you would get 128 bit, but someone in the other thread mentioned people using two chips from Kingston are still only getting a 64 bit memory bus.

XIII, I'm glad to hear that you read my message before placing your order. It will save you the trouble of what I'm currently going through.