HVAC is complicated, there's a reason why companies specialize in providing this service. If you don't mind wiring a bit you might consider hooking a high CFM shuttered fan to a thermostat, install it in a window and block off the excess space. Then pull in cool air from the house, circulate it in the room and set it to vent only above a certain temp. Downside is that unless insulated well you might pour warm air into the house causing the AC to run more, otherwise you are venting your AC air however. Neither is ideal.

Possibly the best would be hook up a swamp cooler to a window, blow cooler air over your rigs, then vent out opposite window. Not too expensive, electrically not too bad, keep the rest of the house separate. Only downside is if you are in a humid climate it won't work and can make excess moisture an electrical worry.

Honestly unless you live somewhere ridiculous, just cross venting with high CFM fans is the best.