I use a Dell R210 ii with a dual port connectx-3 card. This gives it two SFP+ ports. For now it is running pfsense CE. Uses about 30 watts.
Intel(R) Xeon(R) CPU E3-1240 V2 @ 3.40GHz. I have Ethernet running to the ONT and a DAC cable to my 10G switch. I've had Internet as fast as 2G/2G and this system is yawning.
You could use an air-to-air heat exchanger instead of the vent to cool the room and not add humidity.