Just don't do it.
to clean electronics since it doesn't contain the impurities that make tap water conduct electricity. So long as you let the components dry out after a deionized water bath, they should work again just fine. However, even if you dunk your stuff in deionized water, it can still getonce you pull it out into the open air. Likewise, unless you're giving your stuff a bath in a spotless clean room, that water may not stay pristine for long.
I'm pretty skeptical these crypto miners are drying out GPUs in a sterile environment, so we arrive back at my original point: power washing your computer is a bad idea. The last thing you want to plug into a PC is a GPU with a pocket of moisture trapped inside it. These videos should serve as a warning for anyone thinking about shopping for a used graphics card in the next few months as the secondhand market is flooded with crypto mining cards.
Seeing that the massive demand for GPUs is dropping post-Merge, they should be a little easier to find at retail. And with the launch of Nvidia's, expect to see big sales of previous-gen RTX 30-series GPUs in the next few weeks. There's no reason to risk your precious PC with a potentially damaged component in order to save a buck.