You could do a little of both.
A few things:
1. First, get a 6th gen i7-6700k, and matching mobo, not a i7-4790. It's only $20 for 2 jumps in generations, and a latest-gen mobo with the latest connections, and DDR4 memory. You can also save like $300 on a cheaper ASUS MAXIUM VIII HERO, which still has 99% of the features.
2. Don't do a 980 SLI. A
single GTX 1080 should match that easily, avoids the headache that is SLI (not all games even support SLI), is quieter, newer, more efficient, and even leaves room for a 2nd card down the road. I've had experience with SLI, and when you're building a new rig, it's almost always better to go with 1 fast card vs 2 older/slower cards in SLI.
3. Instead of your SSD, consider an M.2 Drive. It's faster than a 850 EVO (SATA) drive, and supported by your 6th gen CPU. The 850 EVO is still a great choice though.
http://pcpartpicker.com/product/3F8H99/samsung-internal-hard-drive-mzv5p512bw
4. For your HDDs, I'd just get a big 2-4GB drive, unless you're buying 2 1-GB drives for a RAID 1. (If it's for RAID 0, get a bigger SSD and HDD instead. You don't need your storage array to be slightly faster at the cost of reliability).
5. Not sure if you actually need the 32GB of RAM, I'd start with a 2x8GB (16GB) kit, as nothing I throw at my system approaches 10GB yet. That's up to you though.
6. I don't know much about that particular PSU, I'd check out the Guide here on Tom's HW. Case you choose is nice to work in.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i7-6700K 4.0GHz Quad-Core Processor ($348.99 @ SuperBiiz)
CPU Cooler: Noctua NH-D14 65.0 CFM CPU Cooler ($72.25 @ OutletPC)
Motherboard: Asus MAXIMUS VIII HERO ATX LGA1151 Motherboard ($199.99 @ SuperBiiz)
Memory: Crucial Ballistix Sport 16GB (2 x 8GB) DDR4-2400 Memory ($65.95 @ B&H)
Video Card: EVGA GeForce GTX 1080 8GB Founders Edition Video Card ($699.99 @ NCIX US)
Power Supply: EVGA 750W 80+ Gold Certified Fully-Modular ATX Power Supply ($84.99 @ NCIX US)
Total: $1472.16
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-06-29 17:01 EDT-0400