Solved Black screen issue - no diag led On

Hello,

It's been a while since I'm building my own setups but this time I'm stuck. At the beginning of the week, for some reason, my computer was starting but only showing a black screen. While there was no CPU/RAM or Boot led turned ON I thought this might be a GPU issue. So I tested with an old card and had the same problem. Tried the embedded display ports and nothing work as well. Lacking further idea I cleared CMOS and ONE time, I ended seeing the Bios splash screen and was able to enter it. But once exited, the black screen came back and I was never able to get my setup to work again. So thinking about a Motherboard issue, I had it changed. Received today, I hastly re-setup everything, installed the CPU, RAM, everything (yeah how foolish of me...) and turned it back ON with the brand new MB to discover... the very same issue.

The setup on its current state is as below:
- CPU: AMD Ryzen 5900X
- MB: MSI B550 Gaming Plus
- RAM: 4x -> G.Skill F4-3600C16Q
- GPU: Gigabyte RTX 2060 OC
- Power: 650W Corsair

I can confirm is that my screen works and the cable as well. I connected a laptop with the same cable on the same scren, no problem here
For the sake of precision also, please note that my screen seem to catch some sort of signal. It does not enter sleep mode and would "flash" at some point but maybe only because of some power going through...

What I tried so far with that new motherboard:
1. Tried to start with no CPU/RAM/GPU with embedded display connected --> nothing displayed (no bios splash whatsoever), CPU led turned ON
2. Connected a CPU (nothing else) --> RAM led turned ON / nothing displayed
3. Connected ONE RAM (DIMMB1 slot) --> Boot led turned ON / still nothing displayed
4. Connect my boot drive --> Boot led still ON / nothing displayed
5. Unplugged the drive, connected a bootable USB drive --> no more diag led ON but still NO display
6. Connected my GPU, still with the USB boot --> still no diag led ON, but yet again nothing displayed...

I must say I ran out of idea. I would be already happy to simply see the BIOS but couldn't achieve that so far.
I haven't tried to clear the CMOS on that new MB, do you think it could be of any interest ?

Needless to say I could appreciate any suggestion. I saw several people getting similar issue but I'm afraid none seemed to found a way around, and I'm starting to imagine why.

Thank you for your help !

Cheers,
Max

Hello,

Just a small insight. That thread can be closed.
To be honest I have no idea what I've done precisely. I decided to check later that issue but not wanting to have parts all over the place I mounted everything back: all drives, all RAM, GPU & so on, but I did that a bit quick so I ended not plugging the power cable to my GPU and still with my monitored connected on the MB MD port. When I get back to it, I turned ON my computer and to my surprise, I saw a message displayed: "please connect your GPU power."
That I did, and I got everything back !
My guess at this point is that there was probably something badly plugged and for some reason the diag leds didn't turned on. I doubt this was related to the HDD as I see no link with display, but maybe something when I plugged the GPU the 2-3 times I did it, despite changing of slot.
Anyway this will be my advice for those facing similar issue: try everything at least twice and unplug then plug back everything.