is quadro fx 580 better then gaming card hd 5670

Hello i am in a weired dilemma. I just bought a quadro fx 580 which is double the price of my gaming card ati radeon hd 5670.

Yet the renders on maya were taking almost equal time . NO difference. Of course the games were almost butchered on quadro, but i know thats not its purpose, but why i am not getting any difference in application render ?

Is it that RENDERS dont use gpu and only use cpu. Gpus are just for better real time viewing or modelling?

please help