HOW CAN GRAPHIC CARD OF HP COMPAQ DC7700 SFF BE UPGRADED

I believe you'll need a low profile video card, which is going to severely limit your options, probably only last generation budget oriented cards. You may need additional hardware, like a riser or bracket, to install the card. I really can't help you beyond that, since I only use mid tower or larger cases myself.

May i recommend the 6670

Did you actually have a setup like this? Would there be power issues? The DC7700 SFF has a 240W psu, and the pci-e slot is rated at max power of 25W.

I am looking to do something like this, and would be happy if a 6570 works (13W less).

Thanks!

Sean