Smoke coming up from pci-e slot

I started to smell a burning smell while mining and when I went to look at my mb smoke started to come out of the first pci-e slot. I have an ASRock 970 Extreme4 running 2 Gigabyte R9 290s. I actually have 3 290s but the mobo was not recognizing the 3rd card plugged into the 5th pci-e slot. After the smoke I immediatly powered down and let it rest for an hour. Removed that gpu and replaced it with another that wasnt being used. Its started up and started to mine but then after about 8 hours or so it started having problems again. I powered it down for 5 hours and then came back and powered it up and it mined for about an hour and the the screen just kept flickering off. I would check my pool and it said I was dissconnected. It continued to flicker off after multiple restarts until eventually it wouldnt even show the uefi bootup screen. And before that it for some reason wouldnt load my ubuntu off my usb drive. I tried to reinstall it to the drive and in the middle of the install process the screen went black. I figured I just had a bad mobo and RMA'd it and have a new one that should be arriving friday. I didnt have another mobo to test gpus but im hoping they are fine. They really only ran a total of 24hrs at 830-860kh/s each. What do you think?