just rebuilt old am2 machine getting hot but not as hot as vista on same machine

[jimbean]

just rebuilt old am2 machine getting hot but not as hot as vista on same machine
ubuntu 13.04
amd athlon 64x2 dual core 4200+ x2
geforce 240gt pcie/sse2/3dnow!
os type 32bit
disk 157.8 gigs

im running psensor from the ubuntu software center
everytime i run a browser game (ie firefox tiberian alliance)
i get cpu temps around 79 celsius
do i get a new heatsink and or are there settings in ubuntu 13.04 that i could tweak
ive already replaced stock cpu fan
and there is thermal paste
and no dust

[jimbean]

removed pcie card and all is fine
using onboard gpu