Question Dual monitor Problem with signal help me guys !!

Aug 16, 2019
Hello guys .
I have a trouble with connecting two monitors on my rig .
At first , i have rx570 with 2 HDMI and 2 DP ports. I have connected my main monitor to HDMI port with Converter HDMI to VGA because my LG monitor doesn't have HDMI output .
So i have try to connect my second Asus monitor with converter HDMI to VGA as the LG . But my pc getting restart and gets reboot after bios boot.
So then i try to connect my second monitor to M/B with VGA cable so i dont need the hdmi converter because i think may be a problem with signals . But nothing happens .
I have install drivers for my M/B and for my APU but nothing , i got only my main screen . I have enable the graphics on board from BIOS but nothing again .
PS : I do format and i can get the dual monitor but when i install drivers for GPU then my On board doesnt show something and my pc doesnt recognize it anywhere , even in device manager . Please guys help me because i need the space of dual monitor , i work on Video editing projects and i need more space on Premiere and After FX .

GPU Radeon rx570 4gb nitro
cpu AMD A8-5600K apu
Mobo Asrock fm2a68m-dg3+
psu 650 vs corsair
ram 8 GB Kigston