No signal problem after cleaning cpu

[Salpereno]

this is how I started cleaning the computer, I removed the cooler and applied thermal paste. I put everything back in place, after that there is no signal notification. The PC works normally, the graphics light up, the CPU fan is spinning. There is nothing I haven't tried since changing the hdmi cable, removing the CPU and putting it back in, I did the same with the graphics card, took it out and put it back in, I did the same with the RAM memory, reset the bios battery, changed power supply, I tried everything. The strangest thing is that I took another graphics card from another computer, same problem. When I returned the graphics card to another PC, the same problem occurred on that other computer. I found an old computer in the attic, I put the graphic card in the third old computer and a picture appeared. What is causing the problem on these two PCs that were working normally? Please help

[Guest]

Would be helpful to list the system parts. 

 

Like what video cards?

What are the specs of 3 systems you've tried?

 

So forth.

[Salpereno]

System Spec :

RX 580 4gb Nitro

Ryzen 5 2600x

Ddr4 4gb RAM 2x

Power suplly gamdias helios e1 500w

motherboard asrock b450 -a pro msi

Power suplly what i tried is xfx 550 bronz

And tried graphic card nivida GT 710 1 GB

Both PC same problem