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Ultimate Self-Starter Thread For New Membeers this should Help you:
EVGA GTX 1080 Ti SC2 ICX Review vs. Gaming X, Xtreme Aorus that mid-plate is held to the PCB with the screws that retain the backplate .. see photos in link
The TIM can act like glue after it has been melted after use then returned to room temps
If you have zero experience disassembling GPUs ... you have jumped into the Deep end with one of these
I just rebuilt some 1080TI FTW3 cards .... 4 different thickness pads are used & reassembly is more challenging that other cards
You may want to work with a shop or a experience friend
EVGA allows you to do this ... but if you damage the card .. that is not covered by warranty