A little more info would help, Do u no ur mother board type? if so download " Mother board monitor " ( MMB ) i think this is the home page " http://mbm.livewiredev.com/
Also could try "SiSoftware Sandra 2002 " (you dont need to no anything like your mother board type 4 this 1 " http://www.sisoftware.net/
Both of these will tell you ur CPU and Case temp, ( sandra 2002 may have the CPU and Case temp around the wrong way. did 4 me )
Also clean out any dust from the fans, And depending on how many u have maby add another 1 or to 2. Also were is your computer sitting? Does it have good room around the case fans, they r not up against a wall or anything.
If you have to open ur case, im just quessing you no about anti-static protection.