Question No screen after new gpu

[DarkDesolate]

I have a pc

MOBO - gigabyte B450M DS3H
CPU - ryzen 5 something AM4
RAM - 2x8gb ripjaws
GPU - GTX 650 and 1660 Super
PSU - corsair CX 750

I removed the 650 and replaced it with the 1660 after which I can't get a post before ran just fine pc powers on lights fans all that but no screen switching back to the 650 gives me the same thing no screen

 

[RealBeast]

I would clear the CMOS and then put the old GPU back in, then restart and remove all GPU drivers. Then change to the new GPU and install the latest driver.

 

[DarkDesolate]

I have an old pc and swapped the gpus it worked just fine then the next time I turned it one no post

System
Mobo: gigabyte B450M DS3H
CPU cooler: wraith prism
CPU: was a ryzen 5 2600 swapped to 5600
GPU: was a 650 swapped to a 1660 super
PSU: corsair CX750
RAM: 2x8gb g.skill rippjaws
Case: some bears case glass front 3 120mm fans

I changed the gpu first worked fine then one day just no post I reset cmos still nothing took it to a local pc repair shop they tested all parts but the cpu and mobo as they didn't have any AM4 stuff so I got a new cpu as the old one when put in a new system did the same thing no post then I swapped in the ryzen 5 5600 and the same thing is happening I'm thinking mobo is dead or something I'm over looking

Side notes the power button now acts weird turning the system on but not off