I think the problem is user settings related. Have you set your Power Limit to +50?
Make these changes:
1. Temperature set to MANUAL and lowered to 75c
2. Power Limit to maximum + value (probably +50)
3. Click apply at the top of the page
Please read > AMD graphics performance
Do not change any other setting. Leave everything else at default/automatic.
85-90 temps are high. It seems your gpu vcore is too high or gpu has a poor contact with heatsink, or it's a fan failure.
Make sure all fans are spinning under gpu load.
Try to set manually vcore values via wattman for all DPM states.
DPM0(idle) cannot be changed by wattman as far as i know
DPM1 - 825mV
DPM2 - 900mV
DPM3 - 1000mV
DPM4 - 1025mV
DPM5 - 1075mV
DPM6 - 1100mV
DPM7 - 1100-1112-1125mV should be enough for 1330mhz. Start from 1100 and try higher values if getting artefacts in games or any stability issues.
Your ideas are both good and correct but i think they addressing the wrong problem.
I think the main issue here is a software bug who causes the GPU to crash, when the Clock begins to throttle. Iam guessing its not AMD's intend to crash the GPU when throttling the clock.
vbios contains many various temp limits as max. temp, hotspot temp, shutdown temp. I guess one of the card's sensors detects critical temp and cause the system shutdown. Don't know how exactly it works because my card never reached so high temps, just saw these values when modded polaris vbios.
But what do you think about that my GPU is absolute stable with the old drivers?
I don't know. Maybe amd did some changes how power efficiency works or older drivers could be just a less optimized for polaris architecture and as result less utilize gpu in some scenarios, gpu is less heating and it doesn't cause the system shutdown. Even 1C difference could be enough between stable/unstable.
By any chance, do you have the latest Intel Chipset and Intel VGA On-Board Driver for your motherboard from MSI Support from here: Support For Z97 GAMING 5 | Motherboard - The world leader in motherboard design | MSI USA
I noticed from the above link that you can download and use a software called GAMING APP. This app can control your GPU card. I also saw Intel Extreme Tuning Utility that can control you GPU card or maybe it was made for the motherboard Intel on board graphics.
If you are using GAMING APP, I would uninstall it and use strictly Wattman. It is possible that app is in conflict with Wattman. IF you have the same problem after uninstalling the Gaming APP then reinstall it since that wasn't the problem.
I have the latest driver for my Chipset and BIOS installed and disabled VGA in BIOS.
I never used any other software to control my GPU beside AMD's driver.