I can't find motherboard or bios vendor, my screen dont turn on aswell
There should be some print on the motherboard somewhere, without the motherboard version we can't help you. According to http://www.tomshardware.com/forum/313056-30-compaq-longer-boots-video it's bad ram, it has the exact same symptoms as you, so check it out. Multiple other sources online point to a compaq evo computer btw.