Q: no signal after apple logo on boot

What specific model Mac Pro?

What graphics card is installed?

When you say " i can't enter save mode and recovery mode" do you mean you see the same thing? That is you see Apple logo and then nothing?

After turning on open the side cover and see if the fans are spinning including the one on the graphics card. Also look for any diagnostic lights lit on the logic board and my the memory modules.'Do y get a startup chime?

Does the Power light remain lit?