Hello:

The graphics card would indeed be compatible by changing the motherboard, there is no problem. But then you have to buy Motherboard + micro + memory (DDR2 is not good for you) so honestly, if you are going to make the investment, do it when you have to buy a graphics card and as I say, you will probably have to change the power supply.

So about what I have indicated, you put an I5 like: Intel Core i5-4670K 3.4Ghz Box BX80646I54670K Processor

And a motherboard like this, which does not have to be this one: Asrock Z87 Pro4 90-MXGPP0-A0UAYZ Motherboard

If you can't afford to change the whole system, I would first put a better power supply and graphics card and then look at selling your graphics card and micro and with them buy a Quad Core. Honestly, I doubt that the latest Counter will only use one or two cores. If that were the case, there wouldn't be much difference between using a micro like yours and an I5 even though the I5 has a higher IPC, and believe me, both the I5 and the FX sweep your micro in games.

I myself with the equipment in my signature have played very well Counter Global offensive, but honestly it bored me and I didn't play it for even an hour. You don't need a top-notch system to play that game.