So.. about the pad mod - the procedure is actually simple, so I was really scared during the mod but not as scared as when I heard for the first time what it sounds like in that case with 3500 RPM at 106C. Even with undervolt it was unusable for me, too hot, too loud and so close to the mem self-destruct limit... So it's probably an easy decision for anyone who do some memory intensive things and/or plan run it non-stop for hours/days, like rendering/science things or just mining (data science things for me).
Just be sure that you have everything prepared - a few torx bits, one Philips, some sticky tape, IPA or ethanol alcohol to clean it all, a good thermal paste and some 3mm, 2mm and 0.5/1mm soft pads, and a sharp knife to cut pads. It's really important to pick soft pads, I would suggest Gelid pads right now, 1 pack of each thickness should be enough (80x40mm). The critical here is 2mm one for the front side, because of how soft those pads are, it could be easily compressed during the delivery, gaps on the front side are 1.5mm for memory 1.25mm for other places, so it could become unusable. I had to use 3mm in one little spot on the front side because of it, so better buy 2x2mm, 1x3mm, 1x0.5/1mm. Just relax and do it, also try to save old pads (I was able to do it) so in case of any problems with the gpu, you'll be able to reassemble it with old pads and use warranty, there's no stickers inside or anything like it.
Now about the temps - if I understand you correct, you ask about the first chart (green/black lines), where stock set up was able to keep the core cooler with lower RPM during first 2 minutes. I think the original thermal paste is actually ok, not the best, but at least average, original pads are extremely soft (even softer then Gelid) but with extremely bad thermal conductivity. So my guess here is - in the beginning you have a 1kg piece of cold metal that should be heated by both core and memory, but if you artificially reduce heat transfer from memory, you're getting more thermal capacity for the core itself. It will only work that way till the heat sink will reach some high temperature and mem reach about 100C. (On the pads thickness - I had that problem with Minus8 pads, not with the Gelid)
Actually I think that Nvidia put those bad thermal pads exactly for that purpose. For reviews you have open test bench, a ton of gaming, a bit of productivity test and no way to actually check mem temp (In HWINFO it became available 3 months after initial reviews), in that scenario you can make FE design look even better compared to other cards, it's smaller, looks cooler and the core runs almost as cool as on all other cards. It's easy to forget to tell everyone that that's because memory chips are in the agony
