DD NV68 Water Block?
 

I have one of these blocks on my BFG6800GT. It dropped my GPU core down from 77C idle to 51C idle. My rig has a XP3200 with a DTek TC-4 block being cooled by DTek Pro-120 rad. The flow order I have is pump, cpu block, gpu block, rad, res, pump. One thing I noticed was the huge difference in ambient temp reported by my 6800 with the new block. With the stock sink, ambient temps were in the 50's. The interesting thing now is that the 6800 ambient temperature seems to be the same as the CPU temp. Is this just a fluke or is the ambient sensor in the same area as the NV68 inlet? I realised that with my setup the base temp for the GPU is going to be whatever temp the CPU heats the water to. But should the ambient temp be just that?
What about putting another rad in the circuit? I am thinking about adding a Black Ice Pro in between the CPU and GPU blocks (it's a tight fit so the Extreme will not fit) how much affect will this give on GPU and CPU if any?

Thanks

Here's my setup 56K beware:


AMS CF-2009

Do you have any airflow over your ram/around the block? Looking at the "left" picture in the link it doesn't appear that there would be much air movement. That localized heat in semi still air could be the cause of the high ambient readings. I don't water cool my 6800Gt and I get ~49-51C idle temps and only ~56-58C after a few hours of gaming (check temp as fast as I can exit the game). This is in a cramped shuttle xpc. I would suggest adding a 80mm etc fan you have lying around to stir the air a bit and see if temps drop.

$0.02

Not sure if I understand what you mean. Are you talking about the system ram or the GT's ram? The ram is covered by the flow from the two fron 120's and the GPU ram is cooled by the NV68 block. The ambient temp reported by the video card is what I am talking about. It is the same temp as my CPU. My systems temp is 6C lower.