Adding an additional GPU for LTC mining I've just recently started litecoin mining on a kind of old AMD GPU.  My motherboard has space for 2 additional cards.  I'd like to drop in a new card specifically for litecoin mining, but...  I'm not sure if the two cards need to be identical.  Crossfire stuff is confusing me.  If I drop in a second card can it be top of the line and still have my old card do some work?
The cards don't need to be identical. Your mining software should identify each GPU and allow you to control/use each one separately.