We ended up sending the GPU back to the manufacturer since it was under a warranty. I think the overheating had damaged the memory – we did not overclock the card. When I connected the GPU to a display, I could see several artifacts. The manufacturer sent us a new GPU after two weeks.
Apparently, if you’re using multiple GPUs, especially the RTX 2080Tis, you should be using the blower fan type. See this 183.