Can the G5 use "special"/faster memory?

[m_gear]

I recently got a new Powermac G5 (the 1.8 ghz, so it uses DDR3200, this I know), and I was looking at adding more ram, when I noticed that there are different kinds one can buy. Some advertize "dual channel" and others advertize something about lower latency, even tho they are all DDR3200. Does this dual channel ram (or a low-latency ram) work in a PMG5? Would I have to replace all my ram with a different type for this to work?

EDIT: And, I guess, would it make any difference?

 

[Sun Baked]

The PowerMac G5 is dual channel DDR (ie 128-bit) where normal DDR is 64-bit.

Just means you need to add it in pairs.

I think the best performance is more memory, rather than faster (lower latency) memory from the overclockers parts bin.

And sticking with memory that doesn't require the heat spreaders is a good idea, if you take a look at the lack of airflow that would be present with a bunch of aluminum clad memory sticks in the G5.

 

[m_gear]

That didn't really answer my question... Does my G5 already have dual-channel DDR in it? So I don't really have a choice, I have to get more dual-channel DDR or it won't work?

 

[Sun Baked]

Originally posted by m_gear
That didn't really answer my question... Does my G5 already have dual-channel DDR in it? So I don't really have a choice, I have to get more dual-channel DDR or it won't work?

Yes the PowerMac G5 is dual channel DDR (ie 128-bit) where normal DDR is 64-bit.

No Just means you need to add it in pairs.

Take two regular DDR memory sticks and read them both at the same time and you get dual channel. And thus need to add the memory in pairs.

ie, Apple's dual channel DDR (128 bit) = PC3200 + PC3200 = 1 PAIR of PC3200 memory sticks

Or just take a matched pair of DDR400, and the most important thing is probably how the OS sees the memory (the EPROM) -- since we don't diddle the BIOS settings.

 

[Vlade]

Lower Latency doesn't mean anything to the G5. On a PC (Maybe if you hacked REALLY far into the firmware of a mac) you can change the RAM timings to be aggressive or conservative. If its aggressive it will give you about a 5% performance increase, but cheap RAM won't work on aggressive sometimes. The G5 is probably set to conservative, so any RAM will do. Go to best buy, pick up some PC 3200 RAM on rebate (in pairs), and stick it in the G5, brand won't matter

 

[Makosuke]

Yes, basically, "faster" RAM these days is only good for overclockers, which also explains the big metal heat spreaders.

In the G5, since nobody is overclocking the RAM yet, there's little point in buying fast RAM. Quality RAM is a good thing, since it'll have less chance of failing or not working properly, but the speed probably isn't an issue.

The heat spreaders are also a disadvantage--I saw a picture of a G5 decked out with spreader-equipped RAM when I was looking into this a little while ago, and there was nearly zero space between sticks. Those flashy OCZ sticks with the LEDs won't even fit under the fans in a G5.

If you really want proof, Barefeats did a comparison test of really snazzy RAM and boring stuff in which the fast RAM showed no speed improvement whatsoever.

 

[m_gear]

Ok, so I don't specifically need Dual Channel DDR for my G5. I just need a pair of them. What is the difference between the Ram marketed as specifically dual channel ram, and the 'normal' stuff? (Even more specifically, the products sold HERE, as it is the closest store to my house.)

 

[hugemullens]

Dual channel ram that you buy in sets is 2 sticks "Perfectly" matched. To get agressive timing on a PC you often need very very tight tolerances on dual channell ram. My PC is an nforce2 dual channel chipset and kingston dual channel set guarnetee's that both sticks will play nice at low timings. This isn't an issue with the g5 since the timings arent aggresive, most any ram works as long as its installed in pairs.