Hi,
Digging it up, as faced similiar issue. I ve got a unit with Xeon E3-1230. System was running fine. I was planning to replace the CPU with Pentium G850. After I did it, there was no singal and after 30 seconds all system fans very super loud. I replaced the CPU back and everything is fine. Default setting in BIOS is "On-board GPU disabled", at least in 1.20, so I guess if you have a CPU with GPU, like G850 or i3 or i5, this might be the problem. BIOS upgrade should be a remedy, but for that you need to replace a CPU with one that does not have on-die GPU.