Its hard to tell what card came with is computer with store bought computers they vary within reason.
it seems it might come equipped with any one of these:
NVIDIA® GeForce GT 620 1GB DDR3 Graphics Card
AMD Radeon™ HD 7570 1GB DDR5 Graphics Card
AMD Radeon™ HD 7770 2GB DDR5 Graphics Card
NVIDIA® GeForce GT 640 1GB DDR5 Graphics Card
AMD Radeon™ HD 7870 2GB DDR5 Graphics Card
NVIDIA® GeForce GTX 660 1.5GB DDR5 Graphics Card
I think it's likely the psu gets changed as well if a more powerfull card is used, but who knows what was in the OPs system since he didnt say...