are you high? its limited because if it uses all of the rtx your pc would have no graphics proccessing and it would be relying all on your cpu (proccessor), in other words, your computer is saving some of the gpu power (likely because your cpu is not as powerfull as your rtx and it is relying on the rtx instead of the processor) and it also be that you dont have much ram, a powerful gpu isnt all you need to run a pc