I have the same problem. Some times my computer turns off itself while I'm working on it and on my screen i get the following message "no signal' The fans work well. They are clean. I've all cleaned. When it turns off itslef it's not eseay to start it again. I'am obliged to plug it out from the wall. Some times I'am obliged to try to start it more tha one time. My computer is ACER. When it starts, it checks with FAT32, after checking, it starts for a while, sometimes it works for long time, sometimes after checking with FAT32 it automaticaly turns off again.
Any help wil be greatly appreciated