For the video issue the onboard gpu is on. Go into the bios turn off muilt monitor support to turn off the onboard gpu and then set the primary output to peg or pci. For the heat issue was there any thermal paste on the after market CPU?? If you added your own there may be to little or too much paste on the CPU cooler. The other issue is the cooler not down tight or the CPU fan not moving. Check in the bios what the CPU fan speed is. To slow of fan speed can cause heat issues.
Thank you. I applied the thermal paste myself, first time I have done it so its likely I did it wrong. I will dismantle and reapply it later. As for the slow boot, I can't find any options for switching off multi monitor support/onboard gpu in bios. however, when I go on device manager on the control panel it only shows the graphics card as the display adapter. can the onboard GPU still be the issue or is there something else causing the problem?