Question Monitor shows No hdmi cable detected, or the same for vga.

[SSLexSS]

Hi! I have an older Dell St2010 monitor. I bought it in 2012, since then, all ok. Suddenly, after I unpluged from the wall everything (cause i use to do it when i leave home for longer periods, just in case of thunders, which didn't happened), my monitor shows this message forever and i cant use it anymore.
What i tried: - monitor's self test and diagnosis - but the monitor works properly.
- I bought new high speed hdmi cable (only one port built-in) , i bought new DVI to VGA cable, none of them fixed the problem.
- i cleaned all the dust from the pc, ports, jacks, video card...etc..
- i removed all the cables, pluged them back, restarted the pc...nothing....
- i tried to start the monitor on the HDMI port and VGA port separately and at the same time, none detected, but the monitor gets image and passes the tests.

What i'm using now, it's a Samsung TV. I dont think this is a PSU problem (i changed it in this year's spring, from 350 W that i used for 7 years almost, to a 450W one - enough for what i use).
If, the power is enough, the PC runs normally on the TV, what's left to do? If the motherboard would be damaged, why recognise the TV, but not the monitor?

Specs:
Intel i5 CPU S760 2.53 Ghz
AMD Radeon RX 460 Graphics - 4gb ddr5
8 gb RAM ddr3
System model XPS 8100
PSU - delux dlp-23ms

These combined, use at most 200 W of 450W.
All drivers up to date.

 

[Ralston18]

My thought regarding: "What i tried: - monitor's self test and diagnosis - but the monitor works properly" and "but the monitor gets image and passes the tests."

By that you mean you can go in to the monitor's configuration and test screens but nothing appears when the monitor is actually in use to display computer output. Is my understanding correct?

If the Dell ST2010 monitor's built-in diagnostics work do remember that that is only one part of the overall monitor circuitry.

What may be broken is the circuitry that handles the incoming video signal(s) from the host computer via the motherboard's built in video ports or any installed GPU cards.

A 7 year old monitor is likely near EOL (End of Life).

 

[SSLexSS]

Yeah, you got it right, I was expecting it's EOL, cause i noticed some slightly burn in at the corners, but untill I buy a new one, I hoped I'd get some tips to make it function for a litle while more.
I read more posts in this forum and i thought i can still do something to make it work a litle more.
Thank you for your time!
I appreciate the feedback.

 

[SSLexSS]

Update: i tried with a different monitor and i got the same result. It seems the monitors are not recognised, only the TV. Any ideas?

 

[throwawayaccnt]

Update: i tried with a different monitor and i got the same result. It seems the monitors are not recognised, only the TV. Any ideas?

How old was the other monitor you tested? How old is your motherboard? Can you tell if your components are powering up correctly when you turn it on? A defective/dying board was going to be my first guess but you're getting a signal from your Samsung TV so I'm perplexed

edit: I missed you mentioned it was a 2012 computer

 

[SSLexSS]

How old was the other monitor you tested? How old is your motherboard? Can you tell if your components are powering up correctly when you turn it on? A defective/dying board was going to be my first guess but you're getting a signal from your Samsung TV so I'm perplexed

edit: I missed you mentioned it was a 2012 computer

Everything is powering up correctly. The other 2 monitors i have tested, are 4 and 6 years old. None of them have hdmi ports, only vga. I got the same results. I bought a new dvi to vga adaptor and cable, nothing changed. When i plug in both, the tv and the monitor, i get the connecting beep from the dvi port, but the monitor cant be seen in dispay settings (none of them). I removed the battery from the motherboard, i left it unpluged for 1 night, second day i got the same result: hdmi to tv works, dvi to vga doesnt work on any monitor. I powered the pc without ram, i drained out the power, i switched the rams, same.reuslt.I have to mention that after i.unplug the monitor and switch back to.the tv, all of my desktop icons are not arranged anymore and they are split to a smaller resolution. So i guess the video card either sees the monitor's resolution, either goes to default resolution cause it cant see anything.
I'm in a total fog...
Antoher thing that i want to mention is that i connected a laptop to the monitor via hdmi, it didnt work, but it worked with the tv.
New dvi to vga failed in both cases, laptop to the monitor and pc to the monitor.