so here is the build:

System Configuration:
Chassis Model: Special Deal Hot Seller - Digital Storm Apollo
Exterior Finish: - Standard Factory Finish
Trim Accents: - Standard Factory Finish
Processor: Intel Core i7 5820K 3.3GHz (Six-Core) (Unlocked CPU)
Motherboard: ASUS X99-DELUXE (Intel X99 Chipset)
System Memory: 16GB DDR4 2666MHz Corsair Vengeance LPX (High-Performance)
Power Supply: 850W EVGA SuperNOVA
Expansion Bay: - No Thanks
Optical Drive: DVD-R/RW/CD-R/RW (DVD Writer 24x / CD-Writer 48x)
Storage Set 1: 1x SSD (250GB Samsung 840 EVO)
Storage Set 2: 1x Storage (1TB Seagate)
Storage Set 3: - No Thanks
RAID Config: - No Thanks
RAID Card: - No Thanks
Internet Access: High Speed Network Port (Supports High-Speed Cable / DSL / Network Connections)
Graphics Card(s): 2x SLI DUAL (NVIDIA GeForce GTX 980 4GB (Includes PhysX)
Sound Card: Integrated Motherboard Audio
HPC Processor: - No Thanks
Extreme Cooling: H20: Stage 2: Digital Storm VORTEX 240mm Radiator Liquid CPU Cooler (Extreme-Performance Edition)
H20 Tube COLOR: - Not Applicable, I do not have a FrostChill or Sub-Zero LCS Cooling System Selected
Chassis Fans: Upgrade Chassis With LED Performance Fans (Blue) (Up to 6 Fans)
Internal Lighting: Internal Chassis Lighting System (Blue)
Airflow Control: - No Thanks
Chassis Mods: - No Thanks
Noise Reduction: - No Thanks
LaserMark: - No Thanks
CPU Boost: Stage 1: Overclock CPU 4.0GHz to 4.4GHz
Graphics Boost: - No Thanks, Please do not overclock my video card(s)
Memory Boost: - No Thanks, Please do not overclock my memory
OS Boost: - No Thanks, Please do not tweak the services on the operating system
Windows OS: Microsoft Windows 8.1 (64-Bit Edition)
Recovery Tools: Windows Recovery Toolkit (Bundled with Windows CD)


was wondering if the 850W EVGA SupperNOVA PSU is sufficient for SLI GTX 980 GPUs with over clocked CPU and liquid cooling system
Should I upgrade to 1000W or is that over kill. I dont plan on doing any upgrades to this system in the next 4 years850W is more than sufficient for that system, and in fact leaves you quite a lot of headroom, you would even be safe to drop the PSU down a notch or two if you wanted but the Supernova is a great QUALITY unit.