I remeber with the second PC I ever owned...a Core 2 quad with an intel MB a hd 5770 and a 450w generic PSU. I left it on all the time pretty much I only turned it off if I knew I was not going to be back home for day. And I got it used and it never died. But I have read mixed feeling on the subjuct on google. For instance it will shorten your HDD lifespan. But then I read that it is not good for the motherboard and the PSU to be turned off and on frequently. If anyone has any thoughts or preferences let me know..