tataklee

At least in my line of work, professional, 3rd party, investigators are step 1 in trying to determine if there is legal liability.  The reports generated are used to correct policies, and decide if it is worth, say, fighting something in court, or if you should just settle.
 
Basically, they are used as a way to identify issues, and possible fixes for those issues, before deciding anything else.  This means that it is in the companies best interest to have an impartial, 3rd party review that is honest.

Getting a high end RTX 4090 for 1.200 USD strikes me as somewhat optimistic. The Strix you picked currently retails for 2.000 USD. 
 
Also, you might wanna wait for AMD to release their Ryzen 7000X3D CPUs, since they will possibly beat the 13900K in gaming performance without melting your PSU. 

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i5-6500 3.2GHz Quad-Core Processor  (£160.99 @ Amazon UK) 
Motherboard: Asus B150M-A Micro ATX LGA1151 Motherboard  (£66.56 @ Ebuyer) 
Memory: Kingston FURY 8GB (2 x 4GB) DDR4-2400 Memory  (£31.99 @ Amazon UK) 
Storage: OCZ TRION 150 240GB 2.5" Solid State Drive  (£52.98 @ Ebuyer) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  (£39.95 @ Amazon UK) 
Video Card: Palit GeForce GTX 980 Ti 6GB Super JetStream Video Card  (£529.99 @ Amazon UK) 
Case: NZXT H230 (Black) ATX Mid Tower Case  (£49.99 @ Novatech) 
Power Supply: Antec TruePower Classic 650W 80+ Gold Certified ATX Power Supply  (£70.44 @ More Computers) 
Monitor: Dell P2314H 60Hz 23.0" Monitor  (£135.00 @ Amazon UK) 
Keyboard: Logitech K120 - UK Layout Wired Standard Keyboard  (£10.99 @ Amazon UK) 
Mouse: Zowie FK1 Wired Optical Mouse  (£48.99 @ Amazon UK) 
Total: £1197.87
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-04-17 12:35 BST+0100
 
This is what I'd be getting.

IMO the thing is right now that both Polaris and Pascal are just around around the corner. I'd wait for their releases before dropping £750 on graphics cards.
 
However, the Titan X really isn't worth it. Because most 980 Tis come with a factory overclock they actually perform better than a stock Titan X.

CX series is pretty bad, CS series isn't great either, RM (not including RMx or RMi) is kinda meh, VS series is terribad. Both the RMi and RMx series are really good.

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i7-6700K 4.0GHz Quad-Core Processor  ($348.99 @ SuperBiiz) 
CPU Cooler: Cooler Master Hyper 212X 82.9 CFM CPU Cooler  ($39.99 @ Newegg) 
Motherboard: MSI Z170A-G45 GAMING ATX LGA1151 Motherboard  ($119.99 @ Newegg) 
Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-3000 Memory  ($79.89 @ OutletPC) 
Storage: PNY CS2211 240GB 2.5" Solid State Drive  ($69.99 @ Amazon) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($47.98 @ OutletPC) 
Video Card: MSI GeForce GTX 980 Ti 6GB Video Card (2-Way SLI)  ($572.98 @ Newegg) 
Video Card: MSI GeForce GTX 980 Ti 6GB Video Card (2-Way SLI)  ($572.98 @ Newegg) 
Case: Fractal Design Define S w/Window ATX Mid Tower Case  ($69.99 @ NCIX US) 
Power Supply: EVGA SuperNOVA P2 850W 80+ Platinum Certified Fully-Modular ATX Power Supply  ($109.99 @ NCIX US) 
Total: $2032.77
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-04-06 13:44 EDT-0400
 
The i5-6400 wouldn't be able to reasonably handle two 980 Tis in SLI.

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i7-6700K 4.0GHz Quad-Core Processor  ($348.99 @ SuperBiiz) 
CPU Cooler: Cooler Master Hyper 212X 82.9 CFM CPU Cooler  ($39.99 @ Newegg) 
Motherboard: MSI Z170A-G45 GAMING ATX LGA1151 Motherboard  ($119.99 @ Newegg) 
Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-3000 Memory  ($79.89 @ OutletPC) 
Storage: PNY CS2211 240GB 2.5" Solid State Drive  ($69.99 @ Amazon) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($47.98 @ OutletPC) 
Video Card: MSI GeForce GTX 980 Ti 6GB Video Card (2-Way SLI)  ($572.98 @ Newegg) 
Video Card: MSI GeForce GTX 980 Ti 6GB Video Card (2-Way SLI)  ($572.98 @ Newegg) 
Case: Fractal Design Define S w/Window ATX Mid Tower Case  ($69.99 @ NCIX US) 
Power Supply: EVGA SuperNOVA P2 850W 80+ Platinum Certified Fully-Modular ATX Power Supply  ($109.99 @ NCIX US) 
Total: $2032.77
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-04-06 13:44 EDT-0400
 
The i5-6400 wouldn't be able to reasonably handle two 980 Tis in SLI.

EVGA W1 are terrible quality - it is NOT for ANY sort of OCing. SeaSonic S12II or XFX TS as a minimum

Stop trolling.

Out of the suggested coolers only the Cryorig H7 is compatible with your case. However, the Thermalright Macho 120 gets my vote.

Stop trolling.

Stop trolling.

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i5-6400 2.7GHz Quad-Core Processor  ($179.99 @ SuperBiiz) 
Motherboard: Gigabyte GA-H110M-A Micro ATX LGA1151 Motherboard  ($41.38 @ Newegg) 
Memory: Avexir Budget Series 8GB (1 x 8GB) DDR4-2133 Memory  ($26.99 @ Newegg) 
Storage: A-Data XPG SX930 120GB 2.5" Solid State Drive  ($44.99 @ Amazon) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($48.73 @ OutletPC) 
Video Card: EVGA GeForce GTX 960 4GB Superclocked Video Card  ($179.99 @ Newegg) 
Case: Cooler Master N200 MicroATX Mid Tower Case  ($39.99 @ Newegg) 
Power Supply: EVGA 750W 80+ Bronze Certified Semi-Modular ATX Power Supply  ($48.99 @ NCIX US) 
Total: $611.05
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-04-02 12:35 EDT-0400
 
Get Win 10 from Kinguin or G2A for around 30 bucks. I basically just switched the PSU and the SSD because both are big no-nos. 

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i5-6600K 3.5GHz Quad-Core Processor  ($239.95 @ SuperBiiz) 
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler  ($24.29 @ OutletPC) 
Motherboard: Gigabyte GA-Z170-HD3 ATX LGA1151 Motherboard  ($94.99 @ Micro Center) 
Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-3000 Memory  ($72.99 @ Amazon) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($48.73 @ OutletPC) 
Video Card: Zotac GeForce GTX 980 Ti 6GB AMP! Omega Edition Video Card  ($619.99 @ Amazon) 
Case: Corsair 200R ATX Mid Tower Case  ($49.99 @ Micro Center) 
Power Supply: EVGA SuperNOVA P2 650W 80+ Platinum Certified Fully-Modular ATX Power Supply  ($74.99 @ NCIX US) 
Total: $1225.92
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-04-02 14:29 EDT-0400
 
For this kind of money you really want a 980 Ti. Even though I didn't include one, you should really get an SSD.

Stop trolling.

No. Quite honestly, statements like that drive me up the wall. Unless he plans to do some video editing, there's literally no situation in which your build would give the OP better performance than mine. 
 
People around here mostly want gaming systems. An i7 with a R9 390 is simply a poor choice if you could get an unlocked i5 and a 980 Ti for the same price. The Kraken is a waste of money and the P2 is a much better PSU.
 
People asking for help here want the best performance for their hard earned money. Not some gibberish about "balanced builds" and "overkill GPUs".

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i5-6500 3.2GHz Quad-Core Processor  ($204.99 @ Newegg) 
Motherboard: Gigabyte GA-H110M-A Micro ATX LGA1151 Motherboard  ($44.99 @ Micro Center) 
Memory: Kingston HyperX Fury Black 8GB (1 x 8GB) DDR4-2133 Memory  ($35.99 @ Newegg) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($48.85 @ OutletPC) 
Video Card: XFX Radeon R9 390 8GB Double Dissipation Video Card  ($299.99 @ Newegg) 
Case: Corsair 200R ATX Mid Tower Case  ($49.99 @ Micro Center) 
Power Supply: EVGA 750W 80+ Bronze Certified Semi-Modular ATX Power Supply  ($48.99 @ NCIX US) 
Total: $723.79
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-28 17:54 EDT-0400
 
This is what you should be getting.

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i3-6100 3.7GHz Dual-Core Processor  ($112.99 @ SuperBiiz) 
Motherboard: ASRock H110M-ITX/ac Mini ITX LGA1151 Motherboard  ($69.98 @ Newegg) 
Memory: Avexir Budget Series 8GB (1 x 8GB) DDR4-2133 Memory  ($26.99 @ Newegg) 
Storage: OCZ TRION 150 240GB 2.5" Solid State Drive  ($61.99 @ Amazon) 
Case: Silverstone Sugo SG13B-Q Mini ITX Tower Case  ($40.99 @ Amazon) 
Power Supply: SeaSonic 650W 80+ Gold Certified Semi-Modular ATX Power Supply  ($62.00 @ Newegg) 
Operating System: Microsoft Windows 10 Home OEM (64-bit)  (Purchased For $0.00) 
Case Fan: Fractal Design HP12-PWM 61.4 CFM 120mm  Fan  ($16.98 @ Newegg) 
Total: $391.92
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-24 15:09 EDT-0400

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i3-6100 3.7GHz Dual-Core Processor  ($112.99 @ SuperBiiz) 
Motherboard: ASRock H110M-ITX/ac Mini ITX LGA1151 Motherboard  ($69.98 @ Newegg) 
Memory: Avexir Budget Series 8GB (1 x 8GB) DDR4-2133 Memory  ($26.99 @ Newegg) 
Storage: OCZ TRION 150 240GB 2.5" Solid State Drive  ($61.99 @ Amazon) 
Case: Silverstone Sugo SG13B-Q Mini ITX Tower Case  ($40.99 @ Amazon) 
Power Supply: SeaSonic 650W 80+ Gold Certified Semi-Modular ATX Power Supply  ($62.00 @ Newegg) 
Operating System: Microsoft Windows 10 Home OEM (64-bit)  (Purchased For $0.00) 
Case Fan: Fractal Design HP12-PWM 61.4 CFM 120mm  Fan  ($16.98 @ Newegg) 
Total: $391.92
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-24 15:09 EDT-0400

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i7-5820K 3.3GHz 6-Core Processor  ($351.98 @ Newegg) 
CPU Cooler: Corsair H100i GTX 70.7 CFM Liquid CPU Cooler  ($112.99 @ Best Buy) 
Motherboard: EVGA Micro 2 Micro ATX LGA2011-3 Motherboard  ($192.98 @ Newegg) 
Memory: Corsair Vengeance LPX 16GB (4 x 4GB) DDR4-2400 Memory  ($74.99 @ Newegg) 
Storage: A-Data XPG SX930 480GB 2.5" Solid State Drive  ($136.99 @ Amazon) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($48.98 @ OutletPC) 
Video Card: EVGA GeForce GTX 980 Ti 6GB Video Card  ($598.99 @ Newegg) 
Case: Corsair Air 240 MicroATX Mid Tower Case  ($79.99 @ Newegg) 
Power Supply: Corsair RMx 650W 80+ Gold Certified Fully-Modular ATX Power Supply  ($79.99 @ Newegg) 
Total: $1662.88
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-23 15:39 EDT-0400

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i7-6700 3.4GHz Quad-Core Processor  ($327.99 @ B&H) 
CPU Cooler: CRYORIG M9i 48.4 CFM CPU Cooler  ($19.99 @ Newegg) 
Motherboard: Gigabyte GA-H110M-A Micro ATX LGA1151 Motherboard  ($44.99 @ Micro Center) 
Memory: G.Skill NT Series 16GB (2 x 8GB) DDR4-2133 Memory  ($56.99 @ Newegg) 
Storage: A-Data XPG SX930 480GB 2.5" Solid State Drive  ($136.99 @ Amazon) 
Case: Corsair Carbide Series 88R MicroATX Mid Tower Case  ($49.99 @ Amazon) 
Power Supply: SeaSonic 650W 80+ Gold Certified Semi-Modular ATX Power Supply  ($62.00 @ Newegg) 
Total: $698.94
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-23 14:59 EDT-0400
 
A tad overkill, but since he uses it professionally the extra oomph certainly won't hurt. And the iGPU will be more than enough for online poker.

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i7-6700 3.4GHz Quad-Core Processor  ($327.99 @ B&H) 
CPU Cooler: CRYORIG M9i 48.4 CFM CPU Cooler  ($19.99 @ Newegg) 
Motherboard: Gigabyte GA-H110M-A Micro ATX LGA1151 Motherboard  ($44.99 @ Micro Center) 
Memory: G.Skill NT Series 16GB (2 x 8GB) DDR4-2133 Memory  ($56.99 @ Newegg) 
Storage: A-Data XPG SX930 480GB 2.5" Solid State Drive  ($136.99 @ Amazon) 
Case: Corsair Carbide Series 88R MicroATX Mid Tower Case  ($49.99 @ Amazon) 
Power Supply: SeaSonic 650W 80+ Gold Certified Semi-Modular ATX Power Supply  ($62.00 @ Newegg) 
Total: $698.94
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-23 14:59 EDT-0400
 
A tad overkill, but since he uses it professionally the extra oomph certainly won't hurt. And the iGPU will be more than enough for online poker.

1 x Western Digital WD Blue   1TB, 64MB Cache, SATA 6Gb/s (WD10EZEX)
1 x Intel Core i5-4460, 4x 3.20GHz, boxed (BX80646I54460)
1 x G.Skill Value DIMM   8GB, DDR3-1600, CL11-11-11-28 (F3-1600C11S-8GNT)
1 x Sapphire Radeon R9 380 Nitro OC, 4GB GDDR5, 2x DVI, HDMI, DisplayPort, lite retail (11242-13-20G)
1 x ASUS H81M-Plus (90MB0GI0-M0EAY0)
1 x Sharkoon VS4-W mit Sichtfenster
1 x Seasonic S12II-520Bronze 520W ATX 2.2
 
€ 590,--

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i7-5820K 3.3GHz 6-Core Processor  ($376.99 @ SuperBiiz) 
CPU Cooler: be quiet! Dark Rock Pro 3 67.8 CFM Fluid Dynamic Bearing CPU Cooler  ($89.90 @ Newegg) 
Motherboard: Asus X99-A/USB 3.1 ATX LGA2011-3 Motherboard  ($263.98 @ Newegg) 
Memory: Corsair Vengeance LPX 32GB (4 x 8GB) DDR4-2400 Memory  ($134.99 @ Newegg) 
Storage: Samsung 850 EVO-Series 500GB 2.5" Solid State Drive  ($149.99 @ Newegg) 
Storage: Hitachi Deskstar 7K2000 2TB 3.5" 7200RPM Internal Hard Drive  ($55.95 @ Amazon) 
Video Card: EVGA GeForce GTX 980 Ti 6GB FTW ACX 2.0+ Video Card  ($629.99 @ Amazon) 
Case: Fractal Design Define S w/Window ATX Mid Tower Case  ($79.99 @ Newegg) 
Power Supply: EVGA 750W 80+ Gold Certified Fully-Modular ATX Power Supply  ($84.99 @ NCIX US) 
Total: $1848.77
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-14 18:00 EDT-0400
 
You could use this video as a reference.
 
 
 

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i5-6500 3.2GHz Quad-Core Processor  ($189.99 @ Newegg) 
Motherboard: Gigabyte GA-H110M-A Micro ATX LGA1151 Motherboard  ($47.98 @ Newegg) 
Memory: G.Skill NT Series 8GB (1 x 8GB) DDR4-2133 Memory  ($30.99 @ Newegg) 
Storage: A-Data Premier SP550 120GB 2.5" Solid State Drive  ($38.99 @ Amazon) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($49.89 @ OutletPC) 
Video Card: XFX Radeon R9 380X 4GB DD XXX OC Video Card  ($189.99 @ Newegg) 
Case: Fractal Design Core 1300 MicroATX Mini Tower Case  ($34.99 @ NCIX US) 
Power Supply: EVGA 750W 80+ Bronze Certified Semi-Modular ATX Power Supply  ($44.99 @ NCIX US) 
Total: $619.81
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-09 07:04 EST-0500
 
I'd get something like that.