M14x-R2, Performance issue diagnosis

Hey Alienware,

Im looking for help with my m14xr2 -i7 3610QM 2.3ghz laptop. it has 12gb of ram and runs windows 7 home 64 bit. Its about 1.5 year old. In past two weeks, I noticed that sometimes when im running games/videos it LAGS a lot for a short time then back to normal, but this keeps repeating, but i dont think its my internet because it happened on different internets that i used and my internet is pretty good, also i tried non-internet apps and it lagged a bit too. so im looking for a diagnosis. ive noticed that the fan appears to be working more of the time than is normal (just based on my subjective impression) so i downloaded cputhermometer/realtemp and it shows that when i boot up the laptop from being off its at about 50 Celsius for the cpu cores. But over time it climbs to about 70 Celsius even if im not doing anything. If im playing some game or etc it will even rise to over 90 Celsius. At the same time my CPU usage ivaries but most of the time its quite low, the cpu usage can be only 15%-20% even though the core temp is about 75-80 celsius, although cpu usage also spikes sometimes after ive been running it for a while. Whats normal temp for this model? and btw yes i have it on flat surface.

if possible i would like to 1. establish whether its hardware or software problem? , 2.if indeed temperature problem, what does this mean? and 3. what i should do about it?

Thanks very much. Alex