Far Cry 4 can't even be played with 1024 * 768 resolution. Not playable means everything below 30 fps. GTA V maybe playable with lowest settings. Assasin's Creed 4 most probably will not be playable, due to bad optimizings on programmers side.
Upgrade ur RAM by buying 1 more 4gb stick
And give clarification on what ur GPU is?
Ur CPU is OK
If ur GPU is an r7 260 or better the rig should probably handle the games
Far Cry 4 can't even be played with 1024 * 768 resolution. Not playable means everything below 30 fps. GTA V maybe playable with lowest settings. Assasin's Creed 4 most probably will not be playable, due to bad optimizings on programmers side.