GPU Bottleneck with lower end CPU's

[Ohlins]

Although my question is a bit general e.g. I would like to know how a GPU bottleneck is calculated or observed. For example in my case, I have an i3-4170 and was thinking of upgrading to a second hand i7-4770 so that I can get any fast GPU with the budget I have. First I was thinking of buying a GTX 970 as I owned one in the past and already know it's a great GPU for the money. If I spend the CPU money on the GPU will I bottleneck my system that much? I mean an i3-4170 + GTX 970.
I currently have a GTX 950.

 

[wakafaka]

Try powerful card with this cpu...is i3 double core but is pci-e 3.0.So take power GPU from a friend and test it with your CPU.Dont see any other option unless someone test it..have u checked uncle google?
https://www.youtube.com/watch?v=z6IwZ79hK2I

 

[Ohlins]

Try powerful card with this cpu...is i3 double core but is pci-e 3.0.So take power GPU from a friend and test it with your CPU.Dont see any other option unless someone test it..have u checked uncle google?
https://www.youtube.com/watch?v=z6IwZ79hK2I

Yep asked the uncle saw the video also read previous articles here on Tom's Hardware forums, just wanted to see if anyone else tried it at least temporarily so as to provide some real world benchmarks not just for GTA V, but in general.