PC doesn't output to monitor.

I applied a 200 mhz overclock using ASUS GPUTweakII to my Zotac RTX 2060 super AMP extreme and increased voltage accordingly. The computer crashed so I turned it off and on again, however it didn't output whatsoever. I cleared cmos and tried again but it still was a blank screen. I originally thought I had fried the card so I tried using my old GTX 1060 and it was still a black screen. My motherboard does not have inbuilt graphics so I can’t do anything in the BIOS. I am completely stuck on what to do.