I've recently acquired an aging iMac (G3/500 DV SE, Summer 2000) with its original 128Mb RAM out of a possible 1Gb. I'd like to replace the single 128Mb DIMM with 2 x 512Mb DIMMs. I know these need to be 168-pin PC100 SDRAM, 10ns or faster, and I know that PC133 is meant to be backwards compatible with PC100.
However I tried 2 x 512Mb DIMMs the other day and the iMac wouldn't boot up (just stayed on a grey screen). Replacing the original 128Mb DIMM brought it back to life.
I read on this page that "just because RAM meets the minimum listed criteria does not mean that it will necessarily function as intended in a particular Mac". This is a bit of a worry. How can I buy RAM off eBay or even in a shop with any confidence? Nobody selling RAM in 2009 is going to have tested it on a 2000 vintage iMac. Is there any way to tell in advance if a given stick of RAM is going to work, e.g. by its maunfacturer, specs, part number, etc.? Or do I simply have to resort to the much more expensive and time-consuming approach of trial and error?