Hey i bought my laptop 5 months ago and it was working very well i was playing games at max res at high frames with low temperatures and by a month ago my laptop is hot like hell I can't even play TF 2 without lag
The videocard is very hot in idle its working in 40 C and in gaming 90 C and when i bought it in BF 3 i had 40 frames and now i can't even get 15
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.