The reason you sometimes need to buy specific RAM, such as the Transintl RAM, is because Apple takes steps to limit their machines to a certain total amount(allegedly for thermal management). For example, the original 12" Powerbook is officially limited to 640MB(128 Built-in/512 added on). The Transintl RAM overcomes this Apple imposed limit.
My Wallstreet is still officially limited to 192MB. OWC sells 256MB SO-DIMMS that are specifically designed to overcome this Apple imposed limit as well. Still limited to 512MB, but what do you expect from a 1998 machine.
Bottom line, if you pick just any old chip, your Mac may not register the full capacity of the DIMM depending on the specific model.
My Wallstreet is still officially limited to 192MB. OWC sells 256MB SO-DIMMS that are specifically designed to overcome this Apple imposed limit as well. Still limited to 512MB, but what do you expect from a 1998 machine.
Bottom line, if you pick just any old chip, your Mac may not register the full capacity of the DIMM depending on the specific model.