Lifetime

I have an Amd Radeon RX580 8gb with a factory overclock and i undervolted it from 1150 to 1020... I've had it for 4 months now and I don't let the temps get over 70 degrees mostly its at 60 degrees underload and idle its at like 26-30. I'm wondering how long will it be before it dies off?

Specs: - PC with Windows 7 Ultimate SP1, all important updates installed - Motherboard: ASRock Z77 Extreme 6 - Power supply: Corsair AX750 - Network card: Asus PCE-N15 11n Wireless LAN PCI-E Card with the newest driver (1008) - Router: Asus RT-N56U with the newest firmware...