Hello Garry,
As a part-time refurbisher of G4 Mac towers, I've bought probably well over 100 RAM modules (eBay) - and by now am getting pretty good at determining what will and won't work.
If a memory merchant - especially one with a big ad or a cute graphic - doesn't say specifically that his memory works for Macs, it probably doesn't.
If you buy from a private seller, get a good look at the picture of the memory. Mac memory looks as if it has space for nine chips across its face, with the centre space left without its chip. This is almost always a tip-off. Occasionally there are exceptions: Avant brand - with a sort of Superman style 'S' on the individual chip - has its eight chips all together (although not quite as close) - but has an extra space at the far right of the module. Mine, at least, work fine. MOSEL VITELIC - with an IBM sticker - has the centre space, but that space is full of little surface wires that will throw you off. Again, mine works fine. Crucial and Lei occasionally show up with the centre space, but with two diagonal slashes end to end across the label (as a wide "x"); additionally, the print seems abnormally small. These do NOT work. The chips on the affected Crucial modules are blank, except for '32MX8 SDRAM'; the usual Crucial modules - which work fine - have a stylised 'MT' along the left-hand margin of the chip somewhere, along with other info.
By far, most of the modules I buy and use are Crucial (or Micron) and they work just fine.
EL PIDA is another brand I've had good luck with, and Infineon, although most 512MB Infineon modules are ECC for some reason (and not suitable) - Infineon non-ECC modules are usually 256MB for some reason.
I should mention that the RAM I buy is CL2 - (512MB PC133 SDRAM) (ever so slightly faster); the RAM I use which comes free with the used Mac is usually CL3 and is made up of many familiar (and unfamiliar) names. If it works, fine; if not, down the 'memory hole'.
One more quick by the way: some older Dell computers use the same SDRAM as Macs; otherwise almost nothing that works in a PC will work in a Mac.
Think that does it...
Jon
