8 beeps at startup and screen stays dark

i have replaced the normail power supply box with a stronger one i have no hard drive plugged , the dvd driver is also not plugged, i only putted 4.512 MB ram and a video card who im not sure if t works...

before you say anything of the following i have plugged both a hard drive or a dvd driver , i unplugged the video card , removed rams one by one ,two by two and all the earlier together..

the pc dont even run bios when it starts it beeps 8 times but the screen is dark and then is working the motherboard.. (if i was blind i would say that is working because it sounds like that)