Question Ryzen 3 1200 system won’t post


Oct 13, 2019
This Christmas I built a new pc with some of the money I got. Since I had enough of my old parts from my original computer to basically rebuild my old computer and have two systems that I could use for streaming, I ordered some thermal paste and started installing the original CPU, RAM, and GPU. I installed everything and when I turned on the system, I got no signal to the monitor. It could be a monitor issue, but I highly doubt it considering that the monitor was working with my new system just fine. I also removed the CMOS battery and put it back in to try and reset the BIOS. I’m gonna attempt to reinstall the CPU and RAM, but how can I check if the GPU is the problem?

The specs for this system:
Mobo: MSI B350 PC Mate
CPU: Ryzen 3 1200
GPU: Radeon RX570
PSU: EVGA 500 Watt Non-modular 80 plus bronze
Storage: ADATA 256gb SSD

These parts have been sitting in there boxes in a closet for a while, if that helps with anything. About two years ago I upgraded the CPU to a Ryzen 5 3600, which meant I had to update the BIOS. That’s why I tried to clear the CMOS. Anything else I can try based on this info?