Quote from: armazingerz on November 30, 2016, 05:48:02 PM

how do you evacuate so much heat from the room? I intend to build 25 rigs, but that's over 20.000W, how could I keep the room moderately cold? Here there can be 38º celsius on the street in summer

Nitromining gave you the math behind it and that gives you a good rough idea of how it will perform - but there's a fair bit of variables that go into the mix.

#1; Whether you're going to control exhaust (such as using a plenum), or just going to have it be uncontrolled
#2; Determine whether you're designing a system to be push or pull for fresh air
#2a; Make sure exhaust and intake are far enough away from eachother to not short-circuit the airflow
#3; Based on where you live, if you can process the air (cool) in some way
#4; Do baffles or other things need to be done to control noise

So in my case, I've got the flexibility that in this room (my testing area), I can basically do almost all of those things - I have a huge amount of filtered air grills for input air. I've experimented with both tightly controlled exhaust air (even more controlled than the typical hot/cold channel you see in datacenters) - here's an example of my Avalon 6 Plenum build:

All the exhaust air is vented out through the ceiling and additional ducting... I also have a direct/indirect evap cooler that can feed the system, but this requires you to be in a dry climate (which I am, in Arizona). Processed air via evap, or industrial misting, or even air conditioning can make a huge difference on performance - so if you are in an arid environment, definitely explore buying or building your own evap solution (it's super simple). The other thing to keep in mind is if you design the system from the start, you can do clever things like have unpowered (except for pump) evap on your intake side, then machines, the powered exhaust fans - so you get the benefit of evap but you're also separating things enough that you don't get the more traditional issues you'll run into with evap and moisture. Plus evap media when running works even better than air filters in many cases...

With the GPU miners, I stopped doing the highly controlled airflow because the thermal load was so much less than BTC that I didn't need to make something so custom - and I like the additional flexibility that the modular cases bring.