I'm looking to upgrade my GPU so I can play Crusader Kings II. Problem is I have a slim tower PC & am not sure what ones would fit & would make CKII work on my CPU. (The minimum GPU for the game is NVIDIA GeForce 8800 or an ATI Radeon X1900 video card)
for a slim pc you will probably have to make sure it is a low profile video card, 7750 or 7770 would be your best bet as they, by far, have the most performance per watt and your power supply probably isnt very good.
edit: your power supply might not be able to handle it. 220 watts isnt very much. the card uses 55-75 watts. any lower end card is going to use 40 watts or more and not have nearly as good performance. you might be out of luck.