No one knows how long it will last at that clock speed...; might last 4 years, might last 4 months, but, my bet would be on 'it'll be fine', frankly.
Take it to whatever clock speed you can get on default voltage, as core temps go up even more quickly once voltage is added...
(Generally, gaming loads give temps about like CPU-Z/bench/stress CPU, where Prime95/small FFTs is the worst case scenario of all for heat...; 10 minutes of Prime95, and you know normally if you cooling is adequate if temps have stabilized.)