So I am planning to change out everything in my computer I will replace my h310m pro vdh plus for a z390 socket motherboard, my i5 8500 with an i5 9600k, I will go higher frequency ram, and change my gtx 1050ti for an rtx 2060 6gb gddr6 192bit, I was wondering, in the country that I am from the z390 socket motherboard is out of stock in every shop, and I am planning to get it used, also I am planning to get the cpu used too and I wanna ask you guys, is it worth it, do you know what I should check on a used motherboard and cpu to see any signs of the motherboard/cpu not working?