The H50 is no better than a high end air heatsink on the i7 920. To get much better temps and go water your looking at about $250 to make it worthwhile. My i7 965 at stock loads at about 55 under prime 95 small FFTs. Thats way more load than you use in games. Try that and see what your temps are. I also have high ambients in my last test, about 80-83F in my room.
Have you read the WC solved at the top of this forum? Good place to start to see what others usefor cooling an i7 920 with watercooling.
Mainly, look at the sizes of radiators we use, then look at the size of the H50 rad. You'll quickly see what I mean. You can't fool physics and the laws of thermodynamics.