As everyone else said, PSU is really required to make a statement, but for gaming upgrade the GPU, maybe hold back on the RAM, 4GB is reasonable for light performance.
Mobo/CPU should be done together, as Battlefield 4 says "6 cores", this is probably exageerated but they may have some reason to say this. I think there's a vid on YouTube that shows the performance with varying amounts of cores, you should check that out and see if 3 cores is still really enough.
Mobo/CPU should be done together, as Battlefield 4 says "6 cores", this is probably exageerated but they may have some reason to say this. I think there's a vid on YouTube that shows the performance with varying amounts of cores, you should check that out and see if 3 cores is still really enough.