I think ASIC is a better way to mine than by gpu. When mining at 1 GH/s in a pool you earn somewhere between 0.00001-0.00005 Bitcoin per day, worth approximately 1 cent. The cost of electricity far exceeds 1 cent per day when mining Bitcoin with a GPU.So it’s simply not worthwhile to mine Bitcoin with a CPU or GPU. Currently the only way to profitably mine Bitcoin is to use an application-specific integrated circuit (ASIC).  It costs less than gpu or cpu.