Question My Computer Will not display but does turn on.

[FHN28]

I was playing a game when both of my monitors lost signal to my PC. It turns on, all the fans turn on and everything lights up. I have reset the CMOS and BIOS and even bought a new motherboard. I RMAd my PSU and MoBo. The HDMI and Display Ports on the MoBo do not display along with both GPUs. I got a refurbished new PSU and the MoBo was sent back saying no problems were found. My GPU then stopped working and Now i am using a older GPU. I have tried 2 variations of cables and Done everything the internet has to offer. I am so close to giving up on what is my lively hood and I am in full anxiety mode. Can anyone Help me? CPU: Ryzen 1700x
GPU: GTX 980ti, GTX 750ti
PSU, Corsair RX 750 (refurbished)
MoBo: Asus B450-F Gaming, Gigabyte GA-AX370-Gaming K5

 

[rgd1101]

so what exact are you try to boot now?
750ti? B450 or the ax 370?

 

[FHN28]

so what exact are you try to boot now?
750ti? B450 or the ax 370?

I am now trying to boot off of the 750ti and b450
Originally it started up and was working with the display for a good 20 min. I went to play some games and thats when the signal was lost.