Graphics card not detected?

Well I know the graphics card works with the computer but to get it working I need to turn the computer off and take the graphics card out and put it back in a few times and play around with it to get it working. If I hibernate the computer I can then turn it on and resume using it fine but if it is switched off I then have the same problem with detection. I get one long beep followed by two short beeps at start up meaning there is a graphics card or monitor failure but both work fine. I didn't emble the computer in any particular order so that might be the problem but I don't know how to reset and solve this problem... If any one can help I will be very grateful!! Also sorry for my grammar I have to write this using an iPod touch. Add me leekspin@live.co.uk if you need more info. Thanks again.