swordbreaker55
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Re:iMac 350/G3 RAM upgrade - 2007/10/25 01:34
RH,
Yes, you can use any combination of 64, 128, or 256 MB modules to make 512. A single 512 MB stick won't work because the system wasn't designed initially to read as much at once.
Memory systems are designed such that they can only use specific densities of RAM. Each stick is set with chips that carry a set amount of RAM. This The amount per chip is referred to as the RAM's density, in megabits. As it happens, the total memory of all chips in one bank (=1 side of a memory stick) can't be more than 128 MB. The iMac has two slots for up to four banks of RAM. Therefore, to get 512 MB, we have to fill all four banks with 128 MB.
Firmware updates can sometimes raise the practical limit of RAM beyond what the spec sheets list. Case in point: Slot-load iMacs had an initial RAM cap at 512 MB which was later raised with firmware supporting higher-density RAM; these same units thus have a max of 1 GB today as a result.
In short, you need to get two 256 MB sticks that are filled with chips on each side. Nothing less will do.
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