ooooh, I have always wanted to do a high powered TEC/peltier cooling project( I did a low powered one in a low end chip it was fun). so the biggest consumer processors out there are the x99 chips, they are 52.5mm x 45.0mm any generic AIO cooler must be able to cover that chip. So, it is reasonable to assume that you will have a very tightly if not under covered peltier. If you sandwich the TEC with copper plates (to insure both sides are transferring/ receiving heat well), and get creative with the attaching on the AIO's waterblock (zip ties or bendable threaded rods) you will have pretty good results.