To make sense of your question some more info is needed. Rad model and type of fans and how fast you run them. Pump Type. WB type(s). TIM used. Arrangement of rad (to determine if your airflow could be improved). There's more to it than you might think. The same stuff will be more or less effective depending on air flow, how well you have the waterblock mounted and how effective the TIM is at transferring heat load. You might want to try fine tuning what you have before spending more.
EDIT. Saw your Koolance Exos post. That is probably the problem. I never use or reccomend "all-in-one" kits and I have not seen anything from Koolance in terms of rads or pumps that are up to par with the stuff I use or reccomend. It looks cool an all but it's far from being an efficient LC set up.