over 5 years. The system was well cooled and was protected by a good UPS and disconnected from the WEB when I was not online (Motorola cable modem had a disconnect switch). If you leave it 'on' ...having an efficient PSU keeps your electricity use down too.
Again...it's all up to you.
My question is, if is bad for the Pc's health to be running 24/7?? I'm not doing any major tasks that requires the processor to be constantly running, but mostly the hard drive that is being accessed. I am currently downloading a series' complete season, and so that takes some time and I have left my PC running for almost 48 hours. I have heard that leaving the PC on for so long can be hazardous, but I'm not really sure. The only thing I know that is okay is to leave the PC on standby instead of fully powering it down. But at this point it's been on for almost 48 hours.