bro,
this is becos ur GFX produce heat and the heat trap inside...
this happen to me before when i first use 88gts.
the amount of heat trap inside and make the air inside very hot..
as u know the chipset is cool using inside air...
if the inside air already reach 40C then how it going to cool the chipset.
thus what i do when i have this is i use evercool Fox 1 and Fox 3
1 is front intake that direct to my chipset and 1 is blowout which i put beneath my GFX direct blow the hot air out instead trapping inside