I don't have experience with that specific version of the silencer, but I'd say the Zalman. By far. My ATI Silencer still keeps my GPU around 70-75°C under load. (Putting 75cfm case fans on the side helped a lot, it was almost 80°C before, and around 95°C stock.) The Zalman Fatal1ty version will be a good choice if you can find a decent price on it. The Thermalright V-1 Ultra (or even non-Ultra if you're looking to save money) will perform very well also.