As the subject says this is a question about the ram supported by this model. Now officially it only supported 512 MB of RAM from what Apple says but unofficially it supports up to a gig. My question is this if I wanted to upgrade the ram in such a model to a gig what needs doing to allow this (any tweaks etc) and would 2x512 MB chips with Cas Latency 3 (PC133) work in it? I do know PC133 memory can also down clock to 100MHz speed but just wanted to know straight if they work instead of buying the memory (albeit cheap as chips now) and finding it doesn't work as is the case with some motherboards.

You need not worry about timing(cas) with a mac since there is no way to adjust it, Just use anything PC66 or higher for 66mhz bus machines, and PC100 or higher for 100mhz bus machines. The iMac uses 1 SDRAM SO-DIMM slot on the CPU daughter card for memory. good luck on finding anything past 512mb's on a single SDRAM SO-DIMM. This is for the original iMac's, please specify what iMac you are referring too. Core 2 Duo 1.86 2GB DDR 667 ASUS P5L-MX Nvidia 8500GT 500/1000

Correction to above. I just looked and it is two SO-DIMM slots, not 1. Thanks. PM9600(1 ghz G4) 512mb RAM 36gb SCSI ATi 9250 PCI

Thanks for the info, was actually referring to the iMac G3 circa 99-02 models. However I also found the info out my self, thanks for the other tid-bit of knowledge though.