Prolonged use under 95c for the 3900x is gonna result in your chip eventaully degrading sooner than what is expected of it but it wont kill it. Just keep everything stock, Disable PBO and dont mess around with the voltages and use the recomended power plan that comes with the chipset drivers and you should be fine. Ideally you should keep temps below 80c if your main concern is the chips lifespan.
Also those indicators showing red or yellow is also normal for a system that is under load.
For example,This is what my 3900x looks like under full load using CB R20 (with a room temp of 30c):
Also with the type of workload that your using your system for, you should really be going with a decent AIO anyway (for my 3900x Im using a cheap 360mm AIO but a decent 280mm would also work just as well). Like in my case when is started learning Blender and doing some hybrid rendering (combined GPU+CPU rendering) where rendering some scenes can at times last for more than 12hours, an AIO was a must cause temps when under AIR cooling just wasnt cutting it anymore for prolonged use under full system load. Eventually also ended up buying a kraken G12 and using that to also liquid cool my GPU (paired with a corsair H55 120mm AIO) to keep overall system temps down during hybrid rendering.
Other than that, the only other thing you should watch out for is your VRM temps cause they can get a bit toasty under constant load sometimes, and if your having temp issues with your vrm being too hot, you can remedy it by simply adding a 120mm fan pushing air down towards your vrm heatsinks (just ziptie it in place), in my case for example i handmade a ducting for a small 40mm pwm server fan (sitting just above the GPUs backplate) that directs air up towards the boards VRM heatsinks, fan speeds are controlled by the boards built in fanspeed manager to keep the speed and noise levels down (server fans are really loud btw, like a mini jet engine taking off loud, so you dont want them running at full speeds)
