The chips can run hotter, but basically, heat kills everything. As for the reference cards, Anything under 65 is fine for 24/7. You aren't going to significantly degrade components in that manner other than the fan. On these cards, the fan or pump will be the first to go imho. The less heat you have in the GPU/HBM2 the less heat that will soak into surrounding components.
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I've avoided mining on my gaming rig because it voids the consumer warranty. 2 year warranty vs 90 Day warranty... on a high end card that costs $1200ish if you are lucky enough to find it in stock... No thanks. I'll retain my warranty. lol. If you have a PowerColor card, its a 1 year warranty regardless of use.
Gigabyte its 3 year, regardless of use
XFX its 2 years for reference, 3 years for their custom card, 90 Day for cards used in mining applications