Monitor wont recieve signal

so i have had this new computer for about a month, i needed some information off my old hard drive from my previous computer so i took it out and plugged it in. the old hard drive had windows xp and the new hard drive had windows xp pro sp2 64 bit, when i booted up the computer the monitor said it wasnt recieving a signal yet i heard the sound of windows loading and heard the noise for some updates for something so i know the computer booted ok. im using an adapter on my videocard to the monitor cable but its also new so i doubt thats the problem, i plugged the monitor into a different computer and it worked fine, i used the same cable and everything. i dont know whats wrong.

yeah you know what i went through all the cables and there was a loose cable from the power supply, and it was the cord feeding the video card so yeah thats what was wrong, i feel dumb. thanks for the help.