[SOLVED] No Signal to monitor, Boot light on motherboard

[beresdavid20003]

Hello.
My sister's computer started losing signal to the monitor after not touching it for a while. Eventually it led to it not displaying anything when turning on (the PC turns on fine, fans spinning, lights working, can't get to BIOS due to the lack of display).

Here are the things I've done:
-Tested the GPU on my own system, worked flawlessly
-Tried new HDMI/DP cables, to no avail
-Tried a new monitor, nothing
-Got a new PSU, still nothing.
-Removed/swapped RAM sticks/slots.
-Disconnected all SATA cables and installed an m.2 with W10 installed on it, still have the boot light on mobo.
-Removed CMOS battery for 5 minutes without power, placed it back.

Curiously, if I leave only one stick of RAM, not in the advised slot (Slot 2), the CPU light stays on. When both RAM sticks are in their correct order, it gets through.

What the hell could be wrong???
Thank you for your answers in advance!

Specs: CPU: R7 2700x
PSU: Corsair AX860
GPU: Asus ROG-Strix-RX570-O4G
Mobo: MSI B450 Tomahawk Max
RAM: Kingston HyperX Predator RGB 16GB 3200MHz

 

[Nephern]

Try to reseat the cpu

 

[beresdavid20003]

Try to reseat the cpu

I'll try installing a new CPU today, if it still doesn't work, am I correct to assume the motherboard is the issue?

 

[Nephern]

do you have another system to test the cpu in?

also can you look over the motherboard and look for anything that looks loose or blown up, anything burnt?

 

[beresdavid20003]

Hi! I managed to reach a conclusion.
I swapped my own CPU in, it POSTed, then I swapped back the old CPU, and POSTed.
After putting the side panel on, it failed booting up again.
I think the way I have to force the side panel on combined with the lack of cable management space caused one of the cables to lose contact, therefore I left the side panel off for now, and it works great.
Thank you for the replies!

 

[Nephern]

good that it posted, you problem is solved?