The Celeron or any other desktop PC would have a heatsink and a fan to keep the cores cool and prevent it from overheating. Raspberry Pi is mostly designed for non CPU extensive work and low power consumption therefore it doesn't need a fan or a heatsink. In 2012, Celeron would definitely generate a block if you run it long enough, most raspberry pi would just die after generating one block. Back in the days you would have suffered a huge huge loss.