Amoveo and Denarius bitstreams are running roughly at about 200W in the current versions. I think with add-on modules kept reasonable I think a max power of maybe 300W is to be expected over all bitstreams. We have run 200W off a single PCIe cable (good quality PSU) but I would not recommend it. Using twin PCIe keeps the cables in the comfortable zone and that doesn't meant using splitters. Use proper off the PSU cables. We have seen splitters melt in the past and nearly go on fire.

Thermally it is probably just about possible to run with air cooling at 200W on CM5 but there are noise and efficiency aspects to consider. Like many performance FPGAs and similar the Arria10 we use has a thermal runaway aspect which means the hotter it gets the more power it takes. Doesn't necessarily mean yet get more hashing but it certainly drops efficiency. With the current liquid cooling coldplate typically we get the Arria10 (2off -200W running) sitting 35-45degC above the ambient temperature that the radiator sits in. So with radiator in a 20degC room the Arria10 die might be around 60-65degC. That is comfortable and good for Arria10 lifetime and reliability. I'd expect an air cooled solution to be more like 90-95degC. Apart from efficiency running at 90-95degC that could be a lifetime limiting factor. At 60-65degC we expect a very long lifetime on Arria10.

Noise on a liquid cooled setup is good. I can stand next to a test rig with 10 boards hashing and talk in a normal voice. That's with radiators and pumps next to boards and not semi-remote outside which can be even more thermally efficient if it is colder outside. With a air cooled setup of the same numbers of boards I would be wearing ear defenders and shouting at people to communicate.