external graphic cards? why not Discrete/Dedicated Internal PCI card?
You can put one PCI-E card in your system, because your motherboard has that. But it does not depend only on the processor and the motherboard only. It depends on:
1. What are you going to do?
2. What is your budget?
3. What Power Supply do you have?
4. What Monitor configuration are you using?
5. What do you like more? nVidia or AMD???