Shut Down or Leave Runnin

This question is subjective and reality.  Some, like me, would say leave it on 24/7 because it's hard on the equipment booting it from cold all the time.  Some will say that leaving it on all the time will wear out the equipment prematurely.  I think both are correct.

If you do leave it on all the time, I would highly recommend a firewall and antivirus program that stays engaged.  Even if you don't leave it on you still need those programs.  I've never in my many years of having rigs had an "attack" that has crippled me.  Those that have issues with spyware, viruses and other like problems are typically visiting questionable sites and downloading porn and other "risky" and not so friendly programs.

Bottom line, if it's not loud and you want to leave it on... do so.  My last rig before this one was considered state of the art when I bought it almost 5 years ago.  I bought the P4 HT processor brand new on the market, Nvidias top of the line GPU, high end SC, high end RAM, high end MOBO... , and it ran continuously for the better part of 4 years with absolutely no issues.  That doesn't mean you won't have issues, but I didn't.  My rig sits in my home office away from the rest of the house so I never hear it.  Eventhough I have 4/120mm fans it's still not loud compared to my last rig which didn't come close to the air cooling I have with this rig.  

I go back and forth on this.  Mine right now is set to go into sleep mode (or is it hibernate?) after several hours of inactivity, where it looks like it is off but boots up very quickly.  I generally keep it in this mode overnight, as I have it set to run updates, run backups, and download a backup of my website (although not each of these activities every night).  It wakes up for this.

If I am going to be doing something that really taxes my system, I might reboot to make sure any memory leaks are taken care of.  If I know I'm not going to use it for a day or so, then I shut down completely.

One thing I do notice, is that when I wake up out of sleep mode, the case fan seems like it is louder than normal.  I can't decide if it really is, or if it just seems that way compared to the silence of being off.  For a while, I did a manual reboot when coming out of sleep mode to quiet the fan.