If you leave your pc on and let it go into sleep mode the idle power consumption is incredibly low and you will most likely not see any difference on your month end electricity bill.Originally Posted by Hiro
As for hardware wear and tear, again won't make much if any difference because the system is in idle, so the hardware isn't under any load. The only time you'll see any form of wear and tear is if the pc runs 24/7 under full load and even then, if its properly ventilated and not getting hot it'll be fine.
