i dont think theres a way to tell my looking at the chip, if it dosnt say on the chip, then you will need to put it in a system to find out. .icecube
There's all sorts of numbers all over the chip but none say anything useful. I was thinking maybe there is some sort of code like the stepping code on athlons which could tell me. There must be someone here old enough to remember!
If you look on the reverse of the card there should be a small white rectangle with two lines of text at the edge of the pcb. On my one the second line reads "300A/66 COSTA RICA" so that should be what to look for.