Hi David, I have done must sugestions done on web pages. Try start without ram, with all hardware disconnected etc. I only hadn't done a Bios clean, but I do not think the problem is there. There is no start at all, to see bios problem. As I told, the only thing seen working after pushing the pwron button is the PS fan. The cpu should be working because, the refrigerator starts to be warm. This is a HP pavillion t000 board PTGDI-LA from Asus. Using pwrbutton and mains power on, simultaneously, the unit starts working normally, (sometimes), as it be at the moment. If I do a reboot, the unit starts normally again. I have done that. It seems that there is not enough power to start, or something wrong on the board. The fan on real panel is connected to motherboard, and also the cpu fan, and they do not start also. Sometimes there is a small movement on cpu fan, upon power button pushing. I have never seen this before. I can say also, that I have replaced some capacitors, 6 that were "FAT". I have cut them, and replace with new ones just soldering to the old pins, just to avoid problems with "hot" and connections thru the holes of several layers of the board. (I have done that in an old IBM, at several years ago, and it is still working normally). Do you know how the board sources power to the fans? Is there a transistor that does a switch effect? If so, the switching action could not being done at all.