Hi all, Quick story: I have a p4 with nvidia geforce card (10+ years old desktop pc), the last two months it started with a strange noice like roar, the front display was decreasing from FF that it was supposed to be, to 7F etc, the pc was getting more and more slower... Until a week ago, when it couldn't even boot, or it managed to boot after long time and struggled to load Windows .. until it suddenly freezed with the well known blue screen and hexademical numbers about video card. Then, I decided to replace the power supply with a friend's one.. the old one is 350w and my friend's one is 240W.. I plugged it in just with motherboard and hd, and it loaded Windows OS perfectly twice... the front display was FF... everything superb.. I thought that I found the problem.. so I bought a new power supply (400W) and I plugged the same connectors but it couldn't manage to boot at all. I could see a very similar screen as below: http://cdn.pcsteps.gr/wp-content/uploads/2014/02/δεν-ανοίγει-ο-υπολογιστής-01.png I plugged in my friend's power supply again and everything was fine! Then, I changed once again the power supply with my new one, and when I power it on, it beeps once loudly and it displays nothing (not even the initial boot messages)... I am in a deadlock since I have to return my friend's power supply.. any ideas??? I am both so desperate and angry!!! Thanks and sorry for the long message.