I will make suggestions, but before I do you MUST provide more information about your media and workflow.
What is your media? (i.e. Red 4k at 120fps or AX100 at 30fps) This makes a huge difference in hardware requirement! The hardware to do the Red 4k is about twice as expensive as the second.
What is your budget? $2000, $5000, $10,000, $15000?
No I will mainly be working with GH4 4K footage, but if possible, I'd love to have the flexibility of working with Red as well, but Red isn't a priority. For now it's mainly to be able to work fast with GH4 4K and be able to export the project quite fast. I'm willing to spend at least $2000 on the main components: CPU, Mobo, Graphics Card, Ram (probably not even including the SSD's / storage) But I'd be happy to spend 2K on an entire build if it will give me what I need since I'm not generally going to be working with RED, or Alexa footage.
Considering your original build list and your planned media and system goals, I would suggest:
CPU: Intel Core i7-5930k ($550)
CPU cooler: Cooler Master Hyper D92 ($45)
Motherboard: Asus x99 Deluxe ($400)
Memory: G.Skill Ripjaws DDR4 32GB (4 x 8GB) 2400 15-15-15 ($520)
GPU: Nvidia GTX 970 4GB ($350)
Main Component Total: $1865
Boot/OS: Samsung 850 Pro Series 256GB 2.5" Solid State Drive ($190)
Data SSD: Intel 480GB 2.5" Solid State Drive ($200)
Data HD: 3TB 7200RPM Internal Hard Drive ($100)
Case: Corsair 400R ATX Mid Tower Case ($110)
Power Supply: Corsair AX860 Power Supply ($170)
Optical Drive: DVD/CD Writer ($20)
Operating System: Microsoft Windows 8.1 Pro 64-bit ($100)
Grand Total: $2755
Any real advantage to having two SSDs? Most builds I see in this forum only seem to have one.
Having an SSD for the OS and 1 for cache and far more uncompressed media such as DNG is often required now days. It really depends on the workflow. Also AE ache works far better on an SSD and I honestly would put most comps there as well if you have 1.