I am currently running:
* Gigabyte Ultra Durable B75M-D3H motherboard (LGA 1155) supporting PCI Express Gen 3
* Intel Core i7
* 16 GB RAM
*Radeon HD 7950 GPU with 3GB GDDR 5
* 1 monitor - Samsung
I recently installed the Radeon HD 7950 graphics card into the PCI-E 3.0 x16 slot to replace a GTX 650 graphics card that I thought was the cause of low frame rates (avg of 40 fps) while gaming. I installed the new graphics card along with the new drivers.
With the installation of the Radeon HD 7950 I expected my frame rates to increase dramatically, but they didn't. Now I am averaging about 50 fps. In Minecraft I run about 60 fps, in Tomb Raider and COD I run 40 fps.
I have set the monitor at the highest resolution. I have checked the video settings in the games. The low frame rate occurs whether I am gaming online or offline.
Run something like driversweeper to make sure there are no Nvidia drivers conflicting, re install latest catalyst suite then check the heat of the cpu. It could be throttling due to insufficient contact with the cooler or similar.