Join Date: Dec 2005
Location: The Netherlands
The biggest difference you will see for gaming is if you would upgrade your videocard. That being said, videocards are insanely expensive at this point so I can see why you would want to upgrade the rest first.
If you go with the 8700k and keep the GTX970 you will only notice a difference in games that demand more CPU power. So sure, with the 8700k it will be faster (in games that make use of it) but won't make as much of a difference then replacing the videocard with a higher end one. But eventually the 4 available threads might become a bottleneck.
That upgrade looks fine but personally I prefer the Noctua NH-U14S over the NH-D15 since it takes up a lot less room and they only differ a few degrees when stress tested.
My CPU history
Main rigs: 386 33mhz > 486 DX2 > Pentium 90 > Pentium 3 666mhz > Pentium 4 1.8Ghz > AMD Athlon 2400+ > AMD Sempron 3000+ > Core 2 Duo E6300 > Core 2 Duo E8400 > Core 2 Quad Q9550 > Core i5 3570k > Core i7 7700k
Secondary: AMD Athlon 4000+ > AMD Athlon X2 3800+ > AMD Phenom II 940 > Pentium G3258 > AMD A10 6800K