I'm not familiar with the heatsink that you're using but I think that 53C idle is pretty hot, even with one case fan, it is hot. I think you should take all the wires out of the way so the case looks clean and neat, also consider getting better HSF solution, something in the lines of ThermalTake SK-7 with a 80mm 50CFM fan. that will cool your new CPU much better than the heatsink you're running. also consider adding more case fans