Manofchalk is correct, here...we simply do not know (esp with Titan being brand new) but for a stock-speed 3930k, you are likely looking at pretty good idle/load temps. My experience in watercooling GPUs (been WC for 10 years, GPUs since the days of Radeon 8500) is that video cards LOVE watercooling as their load temps can easily drop 20-40C, depending on card, ambient and specific loop components. While a GPU is rated to perform at full speed up to 100C+, it's excellent to see a fully loaded GPU running at 38C.
I expect nothing less from Titan as any GPU and TDP can be tamed if you have the right amount of radiator space, pump flow and loop setup. Dual 480's should give you much more headroom than you need to cool CPU+ SLI Titans...so if you haven't bought radiators yet, you might want to calculate what you need unless you are OK with over-radding that much (which is what most people do, anyway).