amd 955. 500 watt psu .16gb ramm.asus m4a89 gtd pro mb.whats best gpu

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Basically, yes. GTX 660 is the minimum requirement for GPU while GTX 960 is recommended GPU for Sniper Elite 4.

Do note that GPU power doesn't follow the same rule as GPU naming goes.
Example: GTX 660 (let's say it's low end) -> GTX 780 (may think that it's medium end) -> GTX 960 (sounds like it's the best than 2 previous ones). But that is not a case.

GTX 780 is far superior GPU than GTX 960 is.
comparison: http://gpu.userbenchmark.com/Compare/Nvidia-GTX-960-vs-Nvidia-GTX-780/3165vs2164

Another example is GTX 750. It's far worse card that GTX 660 is.
comparison: http://gpu.userbenchmark.com/Compare/Nvidia-GTX-750-vs-Nvidia-GTX-660/3162vs2162

Complicated? Yes.
Here's a nice article where all differnet GPUs are lined up by their...

Aeacus

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Basically, yes. GTX 660 is the minimum requirement for GPU while GTX 960 is recommended GPU for Sniper Elite 4.

Do note that GPU power doesn't follow the same rule as GPU naming goes.
Example: GTX 660 (let's say it's low end) -> GTX 780 (may think that it's medium end) -> GTX 960 (sounds like it's the best than 2 previous ones). But that is not a case.

GTX 780 is far superior GPU than GTX 960 is.
comparison: http://gpu.userbenchmark.com/Compare/Nvidia-GTX-960-vs-Nvidia-GTX-780/3165vs2164

Another example is GTX 750. It's far worse card that GTX 660 is.
comparison: http://gpu.userbenchmark.com/Compare/Nvidia-GTX-750-vs-Nvidia-GTX-660/3162vs2162

Complicated? Yes.
Here's a nice article where all differnet GPUs are lined up by their performance. It should help you out in picking your GPU.
link: http://www.tomshardware.com/reviews/gpu-hierarchy,4388.html
 
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