CPU mining IS profitable, just do your homework.
May I know your CPU rig specs?
Take an old i 2600k mild oced to 42 that draws max 170w resulting arround 750 kh/s while mining SRC => aprox 20 SRC/day or 0.015 BTC/day at coinmine.
So 0,45 BTC/month x 123 = 55,35 $ - 15 $ (power cost) =40,35 $ net/month . On top of that add your mining cards' revenue
Keep in mind also that the new 4770k is more efficient and will get you >=1Mh/s.
qed