I had a noisy computer and i traced it to dirt and dust in psu. i took out psu opened it up and cleaned it. After replacing it in computer i bootup but i know its booting but the monitor says no signsl, the led blue light just flashes. I have in stalled a new graphic card and i have a new monitor so it cant be them thats causing the problem. I would appreciate help urgently as i need to do a lot of work on my pc.