Reading around about your laptop, a few things come to mind.
1) Needs thorough cleaning (take apart and clean)
2) Needs thermal compound and thermal pads replaced (seems Acer does a notoriously poor job of applying TIM) simply replacing the TIM has dropped some people's temps by 5C to as much as 15C
3) Use on a cooling pad - they really do help
There are of course other possibilities...
Also, at 5 months, you should still be under warranty, you may just want to contact Acer about possible RMA instructions.