That's normal, you need to set the resolution. The card will default to something like 800x600 until you set it higher.
Right click on the desk top and select Properties and then select the settings Tab. then set the screen resolution slider to where you want it.
So raising the resolution is going to give him better performance? LOL
Oh the irony
Your turn to read the thread properly.
No where does the OP say anything about FPS the thread title is. "After installing my graphic card my computer graphics have become low"
Not Slow but Low.
Truth is the OP could mean either but you are just assuming your take on it is right and taking a pop at someone else based on an assumption you are making about what the op means.