PC Sometimes doesn't Post but not consistently

[EsanuAndrei]

Hello everybody, I have a weird situation that I don't know how to troubleshoot.

 

When I start my PC, the led lights of the power button, the MB and the graphics card light up, the fans start running, seems that everything is fine, but there is no image on my displays, no connection from the Bluetooth keyboard, no other way of seeing that the pc started up. 

I have no beep on post even when it runs fine, and I don't know where it gets stuck due to lack of image displayed.

If I press the power button the PC immediately turns off, which is different than if the pc is in the windows login page, whereas it begins the shutdown procedure and takes 5 seconds to turn off, or when I have to press the button for 5 seconds to force turn it off. 

I bought the PC used, and in the 3 years since I have it I have made a fresh install of windows at the beginning, changed the CPU cooler 1 or 2 years ago with a peerless assassin, the pump was finnicky on the old cooler it came with,  and swapped the 750W Corsair power supply that failed with a Segotep 800W power supply (changing also all the cables), it started turning off in high load, and the issue was solved with the bigger PSU.

At the beginning I didn't have any issue, then it started happening only periodically, then once a week, but new it seems to happen every evening.

I have however upgraded my Hometheater situation and I now have this PC and another connected to the receiver so that I can stream to TV when needed and using the 5.1 setup.

The situation now is that I have my main monitor connected with Display port cable, and the Receiver with HDMI cable. 

Generally I keep only monitor 1 active from windows, although if my wife powers the TV/Receiver, the screen will sometime blink when it detects the new display.

The PC prioritizes the HDMI port when booting, and the DisplayPort only when reaching Windows. Thus when start the PC, I don't have feedback for the first 10 seconds of Boot, and the monitor turns on when it finished booting. 

If I have both displays on and connected for the PC input, and everything runs fine, I can see the MB logo on the TV (through HDMI), and the switch to Monitor. 

However when things don't work, there is no image anywhere. 

 

Usually the problem is solved by turning it off and on again, without any other changes. Sometimes I had to turn off and on 4-5 times until it finally took off.

The worst situation was when it didn't want to start, i cleared CMOS, I disconnected all the cables, took out the vide card, and RAM, reconnected everything, it didn't turn on the first time, but turned on the second time. 

 

The issue is that when it starts working, it can manage all the shut downs/power on cycles without having other issues, so I can't go around disconnecting peripherals or stuff since I can't make it fail on command.

 

For me it's a nuisance, but something that I can manage, but if my wife wants to use the PC when I'm not home, and it doesn't immediately post, she can do a couple of retries, but wouldn't be able to troubleshoot it properly. The most she had to do was disconnect everything for a couple of hours and then it started.

 

System configuration:

Case: Cooler Master TD500 with 3 front 3 top and 1 back vents

CPU: Ryzen 7 5800x

MB: MSI X570 ACE

RAM: 2x16 GB Crucial 3600mhz

GPU: Zotac Gaming 3080TI Halo Edition

PSU: Segotep GP900G, 800W, 80 plus Gold

1 TB SSD NVME Samsung 980 main drive

1 TB SSD NVME Sabrent Rocket secondary drive.

Gigabyte M32Q Monitor connected through Display port 1 and through USB 3.0 cable for the USB hub

Denon X2800H Receiver to TCL TV connected through HDMI port

Asus Xonar U8 MKII external soundcard connected through USB (for fast switching of Edifier speakers and Auditechnica Headset).

A-4Tech cable Mouse.

Logitech MX Keys connected through Dongle.

Now I have a USB C cable and a Micro USB cable not connected to anything that I use for Kindle or Phone, but they are a new/convenient addition. 

2 Xbox Controllers through bluetooth (usually turned off).

 

Any feedback would be highly appreciated.