Hi @mikken7
Even though your normal temp is 35C does not necessarily mean the thermal paste is in good condition, since you have the zero rpm feature disabled probably means your fans are always spinning, therefore giving the illusion that the GPU is relatively cool, when in fact when the actual workload (gaming) starts the temperature probably rises very quickly.
30C room temperature is quite hot, I know because we live in South Africa and in the summer it easily gets about 33C here, which means it is almost impossible to keep a RX 480 under 80C.
Furthermore, since you are stating you have a custom curve I think you should also have your power limit set to +50%, since what people do not realize is once you remove auto fan speed the GPU does not have enough power to maintain proper clock-speeds while giving enough power to maintain the custom fan-speed and keep temperatures below 80C.
Sequentially, like I proposed you should investigate if your GPU is thermal throttling when you are using the stock standard presets (fan speeds to auto, clockspeeds at sapphire defaults, e.g. factory reset settings). Then check if your clock-speeds are downclocking when you get the following scenario: 85-90C with auto fan-speed > 80% and power usage >= 105W in a game with high GPU load; if it is the case you can really consider neatly re-doing your thermal paste with something like DeepCool Z5, otherwise if your stock auto settings is able to maintain < 83C temperature for minutes on end without the clock-speeds dropping bellow 1240-1366Mhz, your GPU is operating within it's thermal specifications which is 90C limit.
Furthermore, it is desired to use a frame-rate limiter or VSync when your GPU is under stress, even though they should be able to operate unlocked, since it prevents thermal compounds from wearing out sooner; and it would depend per game with which frame-rate limits you would want to use. I understand one gets addicted to the low input delay of high refresh rates, but you can actually get better input response by limiting to frame-rates which allows some headroom before any component start to bottleneck.
For example, lets say in CSGO you are getting 160-175FPS when the system is being maxed out, you can possibly get better input response by limiting to 150FPS, or you can even set Radeon Chill between 100-150FPS and you are going to get much quicker input response times and temperature for the specific scenario.
Edit: @Radley your problem can be related to what I described above, or the current driver crashes RX480's/RX580's are experiencing.
Kind regards
