See how your new gpu does first.
You will likely be very pleased.
There really is not any significant boost in cpu power for the gamer using your motherboard.
Here is a list:
http://www.cpu-upgrade.com/mb-Intel/DH55TC.html
$35 might buy you something on ebay like a I5-680.
But, $200 spent on a G4560, a lga1151 motherboard and 8gb of ddr4 ram would perform significantly better.