Games will take the RAM they need. Your performance problem comes from the fact that you only have 1 stick of RAM. You should buy 1 more identical stick. Having your RAM set in dual channel will help the APU access the RAM faster.
thanks, that would have been good to know before i bought the parts and built my pc lol. i didnt know what the diff was between the one stick and two sticks. 16gb of ram here i come then.