80c on load is safe, you should be fine if you stay below 90c for long term use.
Have you tried reapplying thermal paste on the GPU?
Also, is your GPU reference or aftermarket?
what GPU Vendor and what model? - maybe increase the Fan-Curve with MSI Afterburner
i think you need better Ventilation in your system - please make a picture of your open case with the direction the fans blowing -> maybe we can improve there
what CPU cooler do use? maybe a AiO-WaCo can save some degrees due to it blows the hot air ot of system
ps my FX-8150 @4.5GHz runs at 40°C on prime + RX 480 Nitro+ OC on 55°C with new fan-curve