
In terms of game file size, you will need at least 2 GB available.The minimum memory requirement for Crusader Kings 2 is 2 GB of RAM, but have 4 for the best experience - with background applications open 2 GB will be insufficient. Ideally, have a graphics card equivalent to an AMD Radeon HD 6750 for the best experience. The minimum graphics card you can CK2 it on is equivalent to an ATI Radeon X1900. However, the recommended CPU is an Intel Core 2 Duo or better.

The Crusader Kings 2 system requirements ask for a minimum CPU equivalent to an Intel Pentium 4 2.40GHz.
