Originally Posted by rowan

The other thing to be aware of with liquid is possible wicking, where the oil travels along the cable (against gravity) and ends up depositing itself at the other end... in your power supply, ethernet switch, etc.

One cooling method I am currently experimenting with is fast moving fresh air. Filtered inlet at ground level, m/b and GPUs in a sealed box, big-ass fan exhausting out via the roof space. The idea being that even with high outside ambient temps the airflow is still sufficient to draw the heat away from the GPUs. As a bonus it means you do not need to cool the entire room. (Obviously this sort of thing is not possible in a data centre.)