Long Beeping sound when turning on the computer

If it is really coming from your video card usually that would mean it's not receiving enough power like one of the extra pci-e power cords is bad or something. What video card do you have, and how many if any power plugs are in it?

If it isn't the card then it is the motherboard making the beep, if that is the case we need to know your motherboard model to be able to lookup the meaning of the tone.

I no good about computers but I see here is a HP FOXCONN P6055d and my video card is Palit GTX 550 Ti 1gb and my power supply is a Powerchoice 550w. Tell me if I got the wrong answer about the motherboard?

Well I'd think that the most common reason that might happen (and probably the easiest to fix!) is that the ram is either bad or not seated correctly. Try pulling the ram out, blowing out any dust, and reseating it. Might want to try the same with the video card.

Another thing, check your GPU and see if you need to plug in any additional power input from the PSU.

I can't find anything saying that your GPU has a buzzer, so my guess is the beeping you are hearing is from the motherboard, not the GPU. That doesn't necessarily mean that the GPU isn't causing the beeping though. Have you messed with the voltage on the GPU?