Artic Silver needs time to mature before full cooling potential will occur; however, that is absurdly not normal. I would remove the cooler, reapply the paste using the pea or grain of rice method and then install the cooler again. Make sure that the cooler does not wiggle much. My Hyper 212 Evo moves to the side back and forth slightly but nothing bad. There is a little notch that the splitting bracket rests against on the heatsink. It can be kind of difficult to get it there but it just takes some wiggle work. Make sure to not keep removing the heatsink once you have placed it on the CPU. You could possibly have to reapply the thermal paste as lifting it off of the CPU could result in ridge and waves in the paste and introduce air...