I have a athlon 64 bit x2 4200 processor 2g memory

[Bamming1]

I have an old processor but still gaming premium games and a 4850 amd video card wanting to upgrade my video card temporally before pc become obsolete for another machine thats broken. So will gtx 760 or r9 260 cause any problems of weak processor.

 

[Vitric9]

The Athlon 64x2 is the first Dual Core desktop processor. There is a about 4 separate code-named variants of this design so the older ones are not as fast or efficient. The Ahtlon II Dual Core is a bit faster yet though still not able to keep a GTX 760 or R9 270 fed with data. If you plan to upgrade your CPU/MB anyway then by all means get a new GPU. If not then i do not see a compelling reason to get any graphics card in that price range. There are benefits to having DX11 graphics card over a HD 4800 series (DX10) but those benefits would go as far as a HD 7770 or something around that Power as the Athlon just is not powerful enough.

EDIT:
Note: I used an Athlon 64x2 5400+ and an Athlon II 250. I can say that paired with an HD 6870 the performance was not optimal.

 

[Bamming1]

The Athlon 64x2 is the first Dual Core desktop processor. There is a about 4 separate code-named variants of this design so the older ones are not as fast or efficient. The Ahtlon II Dual Core is a bit faster yet though still not able to keep a GTX 760 or R9 270 fed with data. If you plan to upgrade your CPU/MB anyway then by all means get a new GPU. If not then i do not see a compelling reason to get any graphics card in that price range. There are benefits to having DX11 graphics card over a HD 4800 series (DX10) but those benefits would go as far as a HD 7770 or something around that Power as the Athlon just is not powerful enough.

EDIT:
Note: I used an Athlon 64x2 5400+ and an Athlon II 250. I can say that paired with an HD 6870 the performance was not optimal.

thanks