So far so good.
REV. 4.0:
Room Temp 22C (system not in a case)
Water Temp 28C
CPU Temp 36C (XP1700+ T-Bred A 1467mhz 1.85Vcore. Distributed Folding load)
Thats only 8C over water temp and 14C over room temp with a 170GPH pump which is bogged way down. My testing isn't high tech but comparing my other blocks this ones is the best yet. Wish i had some better testing equipment.