Read Carefully Motherboard problem?

[JayCat22]

Let me give ya'll the scenario... I was updating my graphics card drivers and that was through GeForce experience, so when I was installing the drivers, it did everything normal except the screen went black which is also normal but it never came back on. I did all basic troubleshooting such as reseating GPU plugging in all connections such as DP HDMI and power cables and nothing. Then I went to my local Microcenter for a repair and said the GPU failed... fortunately we had a warranty and got a 1660 ti because all the others were sold out. We drove home and still experienced the same issue and again went back. We had a different guy and his methodology was different. Like the last guy I can't remember what he used but it didn't involve its own power like a PCIE power connector and it worked. When he plugged in the 1660 ti nothing and he checked the PCIE cable from the Power supply and its getting power so its not the cable. Then they used a 1070 ti and nothing happened. So, they know the GPU works, and they had no clue and it pointing towards the motherboard. and so we got a new motherboard and CPU because we got a B550 and our old system had a 2700x it is what it is. I rebuilt the system and I saw light and one strange prompt showed up it said unable to post due to Bios or CMOS restarting again or something along those lines. Finally I pulled up the BIOS screen in the new motherboard and everything worked. So could someone help me point me a direction to what it is wrong with my old motherboard because I know it still life unless someone can tell me other wise. 

 

Extra Info the old system is about 10 months and 1 year old. 

Components in old system 

Motherboard - Asus x470 prime pro 

CPU 2700x 

GPU gigabyte 1660 super