PC wont move past dos bootup

Im a techie and am struggling with a certain prob im havin with a pc.
At first i booted up and it went to bootup screen but after memory check it goes to a blank screen.
I tried replacing the hard drive and it still does the same thing,i tried resettin the bios and changing IDE cables and that still failed.
Any suggestions???
answer in here or email me on Matthew@article7.co.za