I've had some of my pc's get down to -10F before with no problems. Heat, moisture, power surges and improperly grounded electrical systems have been my main issues over the years.
I've also done some testing with pcs or laptops in sleep mode vs powering down/up daily. It's often more efficient to just let them go into sleep mode.
Light bulbs tend to be the same way, at least CFl's and incadescent. Not sure about LED's.
