Should be fine. Servers normally stay up nearly 24x7. You might have to eventually worry about fans going out or something, those are usually cheap enough. Main thing is keep everything cool and use a quality PSU that won't damage your system if it goes out and you should be good to go.
If you are really that worried about your main rig, you could probably pick up an older system to do it. Something like an old Dell optiplex with say an i7 2600 or better. Load it up with ram, maybe 16gb or more depending how much the game needs, put a better PSU in there, and let that do the hosting side, then if it goes out, your main system is still good. Which the main system should be ok anyway, but if you just want peace of mind....