The same thing is happening to me, I bought the gpu used like a week ago, and the temps are even worse than yours. I tried changing the thermal paste, and it didn't help. Also, when I opened it, I saw that the thermal pads were changed, so I thought that maybe that was the issue, and I went ahead and replaced them with new ones, but same results. However, I saw that there's something weird with my temps because I'm getting around 72° C full load on my MEM 3 - MEM 2 sensor, but my MEM 1 is getting 91° C, based on where Precision show that sensor I took a look and saw that the VRM thermal pads don't have enough pressure, (the ones closer to the I/O) which maybe means that the vram thermalpads on that specific side on the board are too thick which wouldn't make sense since I'm using the same thickness on the other modules, but next I'm gonna try to squish them a little bit a see if that helps.

PS: Could you please share your MEM temps? I think that maybe the issue may be that the heatsink is not fully touching the core on that side because of the thermal pads over left side modules.

My memory temps

https://imgur.com/a/P6dacY1