Question Computer suddenly stopped displaying, can I be sure it is the GPU's fault?

[javier2409]

I was using the computer normally when suddenly the image completely froze. At first I thought that Windows crashed, but after rebooting I realized that the computer wasn't displaying anymore, although the monitor detects that something is connected because it doesn't give the "no signal" message, it's just that it doesn't get any image so it puts itself into power save mode. I know that the computer is working because I can see the HDD led blinking for some minutes, which means that the OS is booting. And then if I input my password the led starts blinking again.
My motherboard doesn't have onboard graphics so the computer is useless for me right now.
I don't have a spare dedicated GPU to test but I do have an old computer so I moved my GPU (along with my PSU) to that computer, but it doesn't give image there either. It does give image with the mobo's onboard graphics though, so I don't really know if the GPU is not working or I should switch to it in the BIOS settings (I couldn't find an option for that).
Is there something else that I can do to gather "proof" that it is indeed the GPU's fault?
Thanks in advance .

Edit: PC Specs:

• CPU AMD FX-6300
• Motherboard ASUS M5A97
• RAM Kingston Hyperx Blu DDR3 4GB
• GPU: AMD Radeon HD 6770 1GB
• PSU: Topower TOP 650-PM

 

[logikabg2004]

With a system this old nothing is sure but try using a new hdmi cable.

 

[Wynteriscoming]

I had the same issue with much more recent hardware. After looking at some other threads, I saw that some people said this could be that the power supply is not providing the GpU with power or the GPU is dead. I have not found a solution yet and I don’t have any other parts to swap out and test what is broken.
Specs: Ryzen 5 3600, gtx 1070, cooler master 750 watt 80+ bronze, asus b450 plus.