Hello
After a replacement of some components in my computer, it did not start properly
The system consists of:
Graphics card- EVGA 3080 XC3 Black
CPU Ryzen 7 5800x
Motherboard Gigabyte X570 AORUS PRO

Memory G.Skill 32GB (2x16GB) DDR4 3600MHz CL16 Trident Z Neo C
PSU- Corsair SF750
All D-RGB is controlled on the motherboard
The entire system is water-cooled with 2 radiators with 8 Lian Li Uni 120mm fan controlled by Lian Li external controller
The Water pump is an EK-DDC 3.2 PWM (12V PWM pump) in its reservoir housing controlled by the motherboard
Monitor ASUS XG279Q Strix Monitor
Everything works just as it should
The problem just arises when I replace this EK-DDC PWM pump with a newly purchased EK Quantum D5 PWM pump and a separate EK-Quantum Volume FLT 120 D-RGB reservoir. I did the leak test and the pump work. When I connected all the D-RGB cables and to the 24pin connector to the motherboard and turned on the computer, neither the keyboard, mouse show any lights and the monitor has no display
I debugged by disconnecting all cables without display port cable to the screen nothing, tried HDMI cable nothing
I removed the CMOS battery and plugged it in again no difference,
I disconnected all cables in different rounds, fans work, DDR4 memories light up and the pump works but no lighting from the keyboard and mouse and no picture on the monitor 
I unmounted when the graphics card removed the water block and checked for faults on the circuit board, nothing visible
I did a CMOS reset on the motherboard, the mouse and keyboard start flickering at startup with then nothing
I connected the mouse, keyboard, and screen to a laptop and they work
I then changed the CMOS battery, same issues
An online search indicates that either the power supply or the motherboard has stopped working
I bought a new Corsair SF750 PSU och plugged it in, no changes
The keyboard and mouse lights light every now and then then stop
 
I really really hope it's the motherboard fault and a power delivery issue and hope to god it's not my EVGA graphics card!!

That particular motherboard does not indicate postcode
I am seriously thinking about an RMA to EVGA
Need to read up the criteria

Thanks for moving this post
But I recently bought a new X570 basic motherboard, Gigabyte X570 Gaming X did a basic plugin: keyboard, mouse, fan on the CPU. Same results, no picture, no rgb on the keyboard and mouse. 
I do get three red LED lights on the GPU card on start, very quick, the gpu gets warm. But nothing, nothing
GPU kapoot?

MMmmm
I will try this when I get home
I have changed the PSU, the motherboard, tried different combinations of the memory, one and two sticks
Is my Ryzen 7 5800x at fault?
Or are both memory sticks faulty?

Update
I just installed a Ryzen 5 5600G with the built-in AMD graphics
reverted to my original components m
Memory G.Skill 32GB (2x16GB) DDR4 3600MHz CL16 Trident Z Neo C
motherboard Gigabyte X570 AORUS PRO and PSU
I get a display on!! with HDMI connected to the motherboard and not with the display port connected to the graphic card. Keyboard and mouse working 
Actually there is no display at all whilst the graphic card is connected to the PCI slot. Nada nothing. I have to physically remove the card from the PCE 16 slot then restart to get a display on the screen from the HDMI connection. Even with IGPU forced in bios
I can try different PCI settings in the BIOS, but I think there is short somewhere on the card and so no longer working