I have a big water circuit (FSB->RAM->VGA->CPU->FET->NB) with a very big but passive radiator, so my water is lukewarm but not hot (I could take a bath in it after 1 hour gaming, but it wont boil under any stress test...). This radiator could cool my previous system (everything was the same [CPU, motherboard, ect.] and my VGA was a 4870x2 with an XSPC Razor block). The room temperature is ~28-30 C˙, so I think that 40 C˙for the GPU is not a big number when it operates with a passive radiator.
The VRM temperature (100+) is the problem, this GPU temperature (40-50) would be fine for me (it was ~90 with stock cooler, 60 is not a problem).