Originally posted by: akira34
I'd let it warm up to a better temp before turning it on. Bring it inside and let it sit for at least an hour or more. Otherwise, when you power it on, you risk condensation forming, which can kill your rig. To help get it closer to room temp, open up the side panels and blow air (use a fan) into the case. Once it's no longer cold to the touch, it should be 'safe' to power up.
Whenever someone leaves a computer [that I've repaired for them] in a vehicle in the cold we're having now, I advise that they let it 'warm up' for at least an hour before turning it on. I've never heard of anyone having an issue after waiting an hour, or more, and then powering up their system.