There have been small changes made to newer batches of ROG Strix GeForce RTX 2080 Ti graphic cards by the manufacturer, which are causing poor performance and bad contact issues. The good news is that this issue is an easy one to fix and only requires you to remove the four closest stand-off mounts around the GPU. Simply take a pair of flat-nose pliers and carefully turn the screws counter clockwise to unscrew them.
Not sure if you’re experiencing this issue? If there is a small layer of glue around the GPU die, this is what will interfere with the four closest stand-offs on the water block. Removing these stand-offs will not affect the performance of the water blocks.
Right now, this is only a known issue present on ROG Strix GeForce RTX 2080 Ti graphics cards.