GPU not being used fully while having low fps

[Projectice]

I have an AMD fx 6100, 8gb of ram, MSI 7950 twin frozer edition and my gpu is not being fully used when playing games such as Battlefield 3. While playing Battlefield 3 with maxed out settings I get 38 fps and only use 55% of the gpu and only 60% of the cpu per core. When I turn down the graphics setting all it does is turn down the gpu usage. On the lowest setting 46 fps average but only use 38% of the gpu. I have already  turned off v-sync. This problem does not occur in BioShock Infinite where on maxed out settings i get 100+ fps and it uses 99% of gpu. Does anyone know how to fix this. 

[piplupgao]

update drivers

[Morpheus]

might be a driver issue

[MarcusLauk]

I have had a problem with my PSU that bottlenecked my whole computer so do you have a very low powered PSU?

[Projectice]

I am using the latest 13.6 beta driver

 

i have a corsair GS700 PSU

[FluffyNuggets]

Check your CPU clock while gaming