The posts on the backplate are too tall, so when securing the block with thumbscrews, it won't fit tight and give you good pressure. In my case, temperatures can be dropped by around 10C by pressing on the block with my fingers. I have a 2500k @ 4.5 GHz 1.3V and under Prime95 my hottest core hit 68C (58 with proper pressure) with Corsair's preapplied compound. All you need to do is get some washers and put them under the o-rings already on the bases of the posts. I'm afraid the only surefire way of knowing just how thick they need to be is measuring how far the posts stick out above the motherboard, and then buying appropriate sized washers to make the posts flush with the face of the motherboard.