MacPro keeps crashing and restarts. (2013 12Core, 64GB, 1xD500, 1xD700 SSD with an adapter)

Have this obsolete yet very much great working and functioning home unit. My family uses and at times its used for working from home.

I recently replaced one malfunctioned GPU with another used one. I get the following error and not sure if replacing yet another GPU will solve the problem. (not cheap!)

Any help in translating the log would be greatly appreciated. Thanks so much!