upgrade cpu cooler

Hi i have a dell optiplex 9020 small form factor (i7-4790,16GB(2x8GB ddr3 1600),MB: 0xcr8d with intel Q87 chipset) and use for rendering and gaming. average of temp of i7-4790 with defult dell cpu cooler and heatsink is about 75C and peak of cpu temp is 90C and overheat. please recomended me...