I do not see why you want to change the AIO. Change the damn thermal paste. I bet you will find it being hard like cement. Use Cryonaut if you do not want to use Conductonaut.
Please do not put from tube straight to the chip, use a surface area to put it and transfer it with the swabs. You need 1 tiny drop for the GPU & HBM and 1 tiny drop for the cooler. No more.
My Nitro+ (one of the new ones made after May 2018 with the 2 8-pin connectors), with stock paste at Turbo mode 1630/945 had terrible cooling performance on both HBM ram (hitting 80C) and Core temps. When removed the cooler for watercooling (see previous page), the paste was hard as cement peeling. And that was 3 weeks old GPU.
Also I assume you followed the manual and you have placed the radiator properly yes? It has to be vertical with the pipes down.
That is the rule of thumb since the 295X2 if you want for it to work properly.
If you do not follow that simple rule than that is also your issue.
FuryX & 295X2 discussions were long explaining to people how important is to set the AIO correctly for the AMD cards.
I can't fit the rad with pipes down in my case so they're at the top. Does pipes down really work better? I could mod the case.