Windows keeps shutting down

Yeah so while playing newer games, like call of duty etc, my pc lets me play for like 5 mins and then shuts down. I browsed the internet and mostly found that it could be heat related problem. I downloaded speedfan and checked it while game was running. The temps there didnt change, but cpu usage went to like 90%. Oh it also did this once while playing Worms World Party.

My power supply is 400 watts.
Also it shows temperature constantly 45 *C. Is this normal or above normal ?

Please help

Edit:
Field Value
Sensor Properties
Sensor Type ITE IT8712F (ISA 290h)

Temperatures
Motherboard 48 °C (118 °F)
Aux 39 °C (102 °F)
SAMSUNG HD320KJ 37 °C (99 °F)

Voltage Values
CPU Core 1.30 V
+2.5 V 1.90 V
+3.3 V 3.31 V
+5 V 5.08 V
+12 V 2.75 V
+5 V Standby 5.13 V
VBAT Battery 3.30 V
Debug Info F 2D FF FF
Debug Info T 39 48 254
Debug Info V 51 77 CF BD 2B 00 04 (77)

 

Is the pc dusty? If so I would clean it out.

Also may be helpful to post in hardware forum.

 

I suggest you reseat your CPU heat sink and fan with some new thermal paste, if that doesnt work try running the game with your pc on its side and a big house fan blowing into the case to keep it cool.

If this works then it heat related if not

Maybe it is a dodgy powersupply which is kealing over when your CPU is underload.