Graphics cards are designed to be able to work under 100% load pretty much indefinitely.
There's basically 2 reasons your graphics card breaks from 'overloading':
#1: Your card isn't getting enough ventilation; Your fault.
#2: Your card is a defect; It'd happen eventually anyway.
Not including vsync in some parts of the game is really not such a big deal.
Vsync isn't even there to maintain your card.
It's for eliminating screen tearing.
There's basically 2 reasons your graphics card breaks from 'overloading':
#1: Your card isn't getting enough ventilation; Your fault.
#2: Your card is a defect; It'd happen eventually anyway.
Not including vsync in some parts of the game is really not such a big deal.
Vsync isn't even there to maintain your card.
It's for eliminating screen tearing.