How can I tell if I have ECC or non-ECC memory?
For SDRAM or DDR memory, just count the number of small black chips on one side of your existing memory modules. If the number of chips is even then you have non-ECC. If the number of chips is odd then you have ECC.
For RDRAM/Rambus memory, there is a heat spreader covering the chips so you cannot count them. For this type of memory it will say on the sticker "ECC". If it does not say "ECC" then it is non-ECC.