Hi gents, hope everybody is doing fine!

Since soliciting your greatly appreciated help at the beginning of the year I had to postpone my multiboxing adventure for work reasons. More recently things have been quiet and I want to get to it now that I have a chance.

Would you please do me the favour and look over the build we discussed at the time and highlight any changes that you think are in order given new developments? My main question is around GPU and Monitor:

1) 10-series GPU
- I guess it makes sense to go with a 10-series. 1070 or 1080? And then which of the 40 models??
2) Monitor resolution
- For cost and space reasons on my desk I am leaning away from a 4K 40’’ monitor now
- I understand that refresh rate (60Hz or more) and resolution (1080 or 1440) are the main factors in addition to the size of the monitor but I am not sure what I should go for. I guess above 27’’ I am fine with a 1440p and wow would look beautiful enough?
- Let’s say I am looking at a 27’’ or 32’’, should I go for a monitor that can do more than 60Hz at say 1440p? Would I be benefitting from that (in wow or other games)?
- Also Ultrawide would work well for my work-related stuff but I understand they are usually 60Hz, although some seem to deliver 75Hz at 1440p. Does wow support Ultrawide and what is your opinion on that in general?
3) Z170 vs X99
- Do I need to consider an X99 setup at all?

Here is the build we discussed at the time:

1) CPU: Intel Core i7-6700K 4.0GHz Quad-Core Processor ($369.95 @ B&H)
2) CPU Cooler: Corsair H100i GTX 70.7 CFM Liquid CPU Cooler ($112.99 @ Best Buy)
3) Motherboard: Asus Z170-A ATX LGA1151 Motherboard ($142.98 @ Newegg) – Same as #1
4) Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-2133 Memory ($69.99 @ Newegg)
5) Storage: Samsung 850 EVO-Series 250GB 2.5" Solid State Drive ($87.89 @ OutletPC)
6) Storage: Hitachi Deskstar 7K2000 2TB 3.5" 7200RPM Internal Hard Drive ($56.95 @ Amazon)
7) Video Card: EVGA GeForce GTX 980 Ti 6GB Superclocked+ ACX 2.0+ Video Card ($609.99 @ NCIX US)
8) Case: Corsair 750D ATX Full Tower Case ($145.44 @ Mac Mall)
9) Power Supply: EVGA 850W 80+ Gold Certified Fully-Modular ATX Power Supply ($109.99 @ Newegg)
10) Monitor: Wasabi Mango 40" UHD400 4K Monitor + Remote ($632.90)

Thanks again for taking the time to read and think this through!!