strange behavior if HDMI monitor plugged

[chriz74]

The machine is an Asus x301a with hd4000 graphics, the bios is msr unlocked and advanced menu unlocked.
I am using the machine for hackintosh

 
This is what happens if I plug the external monitor and boot:


The PC posts to external monitor, then after DSMOS arrives and framebuffers are initialized the internal screen lights up but no image is shown, image only in the external monitor
This is what happens if I plug the external HDMI after post at clover menu or even when the system is loaded.

https://youtu.be/mbCwRfDsDLI
internal already lit and image is shown after DSMOS and framebuffer initialization.

 

Setting primary display to IGFX in bios doesn't change behavior.

 

Is there a way to mod the bios to tell the machine to show the internal screen at boot instead of the external one?

[chriz74]