Several dead video cards and don't know if it's just bad video cards or a bad motherboard

So I recently rebuilt my system, and replaced everything but the case(including psu) and the graphics card (which was the newest part from my old system). Put it all together, installed windows 10 and everything worked great. However, in our move my old surge protector had been lost, so I went and bought a new one. I then powered down my computer, unplugged it from the wall and replugged it into the surge protector. When I booted the system back up the display didn't come on and I got a beep code from the motherboard. I looked up said beep code and discovered that it wasn't detecting a gpu. I tried reseating it, checked the power connectors, reseated the RAM, even took out the CMOS battery to try to reset that. The fan would always work on the gpu but it would still give me the beep code and never display anything. I couldn't check any of the drivers or anything because the motherboard I bought doesn't have onboard graphics. I figured that maybe the gpu had just died since it was kinda old, so I bought a new graphics card, installed it and the display came on and everything worked first try. Awesome. That is until my wife and I left for a week about a month or so later. Before leaving I powered down my system and decided to unplug it from the wall just in case there was a crazy storm or something. When we got home I plugged it back it and booted it up, only to hear that same beep code and a blank display. I reseated everything again, and nothing. Still dead. I thought maybe it was something to do with the psu but I checked it, and even checked the wall outlet but all the voltages are within the normal range. So basically the only things left I can think of are possible bad airflow and thus overheating (because the fans in my case could be dying as they are kind of old) or a bad motherboard, but I'm not sure how to check either of these and I don't want to get a new video card only to have it die again to unknown reasons. Is there anything else I can check to figure out what the problem is? Also, if there is any other information I can provide to help out just let me know.

System specs:
Motherboard: Gigabyte AMD FM2+ A68H GA-F2A68HM-H
CPU: AMD Athlon X4 860K
RAM: Kingston 16GB (2x8GB) 1866MHz DDR3
HDD: Seagate 1TB HDD
GPU: MSI ATI Radeon HD6450
PSU: Raidmax 500W