So I currently own a Dell Vostro 3450 featuring an off-board ATI Radeon HD 7650m (previously 6630m) GPU.
My issue relies mainly in it's performance loss regarding FPS drops and the fact that I'm no longer able to 'glitch' it as I used to, and it used to work.
What I'd do is: as soon as I noticed a game didn't run as smooth as it was meant to, I would unplug the power supply, the CCC asked me if I would like to switch to the onboard GPU, I confirmed, and then manually switched back to the ATI GPU. It would surprisingly work, as it eliminated mouse delay and significantly increased FPS foi games such as L4D2 and COD:WAW.
Now I can't do it anymore, and reinstalling the graphics card's software didn't seem to make a change.
I would be much appreciated if anyone with a hint or a clue of what possibly causes this problem could help me out! =D