Sooo, i recently heard about this gpu - gtx 980 and i thought that it would be good to replace my old hd 5550 with this one.

Solution
Stick with something like the GTX 950 or R7 370. Both will be worlds better than your current card, will support much newer games and API's, will be much cheaper than a 980TI and shouldn't be be terribly bottlenecked like the 980 would be with your CPU. There may still be a slight bottleneck, but it should be tolerable.

If you want something with better performance than those can provide, you're going to need to upgrade the whole platform.
Stick with something like the GTX 950 or R7 370. Both will be worlds better than your current card, will support much newer games and API's, will be much cheaper than a 980TI and shouldn't be be terribly bottlenecked like the 980 would be with your CPU. There may still be a slight bottleneck, but it should be tolerable.

If you want something with better performance than those can provide, you're going to need to upgrade the whole platform.
 
Solution