My laptop (an HP) has got a dodgy power supply with a broken cord.  I've got an old power supply (also HP) with the same size plug but they have different output rating...

Original power supply output 18.5v 3.5a and 65w
old power supply output 18.5v 8.5a and 120w

Can I use the old power supply with the high amp and wattage rating and will it cause any problems (overheating etc)


Edit:  The battery is stuffed and doesn't charge at all, in case that makes a difference to the anwser.