DDR SDRAM - 8 DRAM chips vs 16 DRAM chips - what happens?

I'm looking to add 2G RAM to my G5 1.6 GHz - specs say I require 2 x 1 GB DIMM PC2700 DDR SDRAM (or faster, ie PC3200).

However most DDR RAM these days have only 8 DRAM chips on them, ie each DRAM chip is 1 Gbit. The Apple specs say each DRAM chip must be 512 Mbit, which would mean a DIMM with 16 DRAM chips, 8 each side. But DIMMS like this seem to be an almost extinct species.

So - what would happen if I put in a DIMM with 8 DRAM chips on it? Would the Mac not recognise it at all, or only recognise half of it (ie only 512 MB of the 1 GB would be accessible)?

Thanks.

G5 Desktop PPC 1.6 GHz, Mac OS X (10.4.10)

Posted on Nov 11, 2007 3:06 AM

Reply
1 reply

Nov 11, 2007 3:50 AM in response to Brendan Jones

Hi-

What you're referring to is high density (fewer "larger" chips) DIMM's and low density (more "smaller" chips) DIMM's. PC DIMM's are often high density, as are "value" DIMM's.

Mac specific memory is usually low density. Using higher density DIMM's will often times result in the DIMM not being recognized at all.

The following explains Mac memory module configurations:

http://developer.apple.com/documentation/HardwareDrivers/Conceptual/HWTechRAM/Articles/RAM_concepts.html#//appleref/doc/uid/TP40003898-SW3

Mac specific memory isn't hard to find. Check the following:

http://eshop.macsales.com/MyOWC/Upgrades.cfm?model=182&type=Memory&TI=3759&shoup grds=Show+Upgrades

http://www.crucial.com/store/listparts.aspx?model=Power%20Mac%20G5%20%28Single%2 01.6GHz%20DDR%29

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DDR SDRAM - 8 DRAM chips vs 16 DRAM chips - what happens?

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