Well, I'm not too sure how the GPU could affect ping, but I guess anything is possible.
Another thing you might try is opening up console (hitting the `/~ key usually does the trick, if not, you have to enable it under [Options>Keyboard>Advanced] and checking [enable developer console]) and putting in these commands:
rate 20000
or
rate 30000
Higher is used for better connections while a lower number is best for a slower connection.
Then try:
cl_cmdrate 100
cl_updaterate 100
This has fixed my pings and helped my shots register more often.
This is changing the number of times your computer sends and receives data.
I hope this helps!