Screen goes entirely black with Rtx on.

I like to play on my worlds on my pc using the Crystal Palace RTX texture pack. But sometimes, rarely, when the RTX is on, my screen will all of a sudden freeze, and then resume, but now the whole world is black. Because of this, I turn the RTX off, and all is normal again. But then when I turn it on again, now everything is still going to be dark, unless I restart MC. 

My card is a 2060 with a clock of 1.4 ghz