Question No signal (used motherboard and cpu)

[soulshd123]

Hey, I am going crazy not knowing what is broken. I cannot get a signal to my monitor.
parts
I5 6600k, Z170 gaming motherboard (both CPU and motherboard are bought used)

3060, HDD 1tb, HDMI cable, psu (750w) modular and ram 2666mhz ddr4 (all bought new)

I had ran the PC on a new CPU and motherboard and everything worked fine, until I swapped to a used motherboard and CPU where I cannot get a signal. The motherboard lights up when turning on and GPU also powers up and CPU fan. However, the monitor does not display a signal. I have tried swapping HDMI cable slots and cable, swapped ram, ram slots, GPU slots and GPU, rechecked all connector (8pin CPU, 8pin pcie, CPU fan plugged, 24 pin plugged and HDD plugged). I tried doing a cmos reset, with taking the battery out and putting it back in, tried shorting the cpu_ov connectors (3 pins), rebuilt the whole thing, checked the CPU pins, checked for any cracks in motherboard.

the only question I have is does the CPU_OV need a jumper? because my motherboard has no jumper on the CPU_OV pins, its sitting naked. Is this the reason for there being no display signal

could this be the problem even though I tried restting bios


also have tried swapping HDMI cable to just motherboard and no gpu

 

[Fix_that_Glitch]

Bottom left corner of your motherboard. What version is it?

 

[Fix_that_Glitch]

Are you getting any trouble codes/lights?

 

[soulshd123]

Are you getting any trouble codes/lights?

It doesn't get anything, no signal on the monitor, the motherboard lights turn on, GPU, and cpu fans. And it doesn't say what version the motherboard is just says "Z170 PRO GAMING"

 

[Fix_that_Glitch]

What concerns me is that your motherboard is not posting any trouble codes in it's led window. If you had a bad cpu it would give you a cpu trouble code/light Have you tried unplugging everything, mouse, keyboard, gpu, any external speakers, usb, except for one stick of ram, and only monitor plugged in to onboard video port?