for occasional gaming (on Mid/Low) my specs: cpu Intel i3 2100 3.10gHZ,mobo Gigabyte Z68M-D2H, RAM Kingstong Hyperx Blu 8 gb 1333Mhz,monitor Asus VH238 LED 23",PSU Thermaltake TR2 500W , Ihave seen on Amazon a EVGA GT640 110$ and a Asus HD 7750 110$, Both PciE 3.0 i dont know which one is better but my mobo is PciE 2.0 ..Bottleneck??