there's most definitely no 8580 in that one, they weren't used in those older models. they can be found in the newer grey 64c's and 64g's. even then, you can't tell just by looking at it. with a 64c though you can look underneath though the vent, if you're able to see the circuit board through the vent then it has an old board and is not an 8580. you need to buy a newer model for the other SID chip.