That's a good question, I would guess that it's around 40 degrees celcius in there but you motivated me to move a thermostat into the room to monitor it.    One of thing things I was asking myself today is if the TDP of gpu's includes the power needed to spin the fans.  IE: If I have 30 gpu's at 100% load and their TDP is 115 watts, then we can hypothetically assume that their wattage is going to be 3450.  It's not going to be obviously but let's just make the math easy.  Now does that TDP include the fans at 100% or does that TDP not take into account the fans at all.. Will it be 3450 with all of the fans at zero or will be be 3450 with all of the fans at 100% or will it be somewhere in the middle?