If gaming only, I suggest you to spend more on GPU instead of CPU, CPU overclocking doesn't bring significant performance boost, it can be none at all if the games you play isn't CPU demanding.

Intel Core i7 6700K - RM 1444
Asus Z170M-PLUS - RM 517
Kingston HyperX Savage 16GB (8GB x 2) DDR4 3000MHz RAM - RM 423
XFX RX 480 8GB GDDR5 GTR Triple X - RM 1329
Samsung 850 PRO 120GB SSD - RM 399
Superflower Leadex Silver 550W - RM 339
Corsair Hydro H100i V2 - RM 508
Corsair Carbide 88R - RM 226

Total: RM 5185 (ETech price inclusive of GST)

650W is recommended for RX480 CF but the mobo doesn't support dual PCIe 3.0 x8 speed when 2 of its PCIe 3.0 slots are occupied, one will run at x4 mode only, this will slow down the card by a huge margin (bottleneck by PCIe slot).

We don't have many Z170 mATX mobo choices to make in Malaysia, it is either you go all in with Asus Maximus VIII Gene (supports dual x8/x8 mode, around 1.2k) or get an ATX mobo and ATX case.

Intel Core i5 6402P - RM 707
Gigabyte H110M-DS2 (D4) - RM 276
Kingston 8GB DDR4 2133MHz Value RAM - RM 145
PowerColor RX 470 4GB GDDR5 Red Devil - RM 899
Kingston SSDNow UV400 120GB SSD - RM 165
WD Blue 1TB HDD - RM 209
FSP Hexa+ 550W - RM 188
Tecware F3 - RM 125
BenQ GW2270 - RM 379

Total: RM 3093 (ETech price inclusive of GST)

Whether it can last for 3 years or not, nobody can give you a guaranteed answer, it should be fine provided you aren't too picky on the graphics settings that this rig can handle.

why 970? why don't go straight 1060?

I need to know your ITX case model because the clearance available (especially for GPU length and height) is different for each ITX case so I can choose the correct hardware.
Why GTX970 and RX480 in comparison? It should be GTX1060 vs RX480, the GTX970 is out of the league already.

GTX1060 is on par (or slightly faster) with GTX980 currently, so no point getting the older GTX970 if you have enough budget for GTX1060.

GTX1060 leads in DX11/OpenCL gaming now while RX480 performs better with DX12/Vulkan, both have pros and cons, but GTX1060 can be as low as RM 1219 (if you buy via Lazada/GemFive coupon code then it can be even lower), so your call here, RX480 could be the best buy if it is priced correctly locally but AMD MY seems to be adding more nails in their coffin by pricing the card at such price tag 

Intel Core i3 6100 - RM 480
Gigabyte H110M-DS2 (D4) - RM 276
Kingston 8GB DDR4 2133MHz Value RAM - RM 145
Palit GTX950 2GB GDDR5 Single Fan - RM 609
WD Blue 1TB HDD - RM 209
FSP Hexa+ 450W - RM 166
Tecware F3 - RM 125

Total: RM 2010 (ETech price inclusive of GST)
Yea that's because most of the games are still using DX11/OpenCL API currently, only few titles like Hitman 2016 and Doom are using DX12 and Vulkan API.

If you get RX480 then it will be more future proof, probably in 2 years time and you will see it starts shining when DX12 and Vulkan take over as the main API for PC games.

If you can save more and get GTX1070, then of course it will be much better, there isn't any competitor from AMD side yet for high end GPU until Vega arrives later this year or early next year. Always go for a better single high end card instead of running multiple mid-range cards, CF/SLI issues are still there and it is not always up to the performance that we are hoping to get (bad scaling, no multiple card support etc).

Among these 4 GPU, which one is the better choice providing they are come with 3 years local warranty and the price is different +- RM60 only?

1) Gigabyte nVidia GeForce GTX 1070 G1 Gaming OC

2) Asus nVidia GeForce GTX 1070 ROG Strix OC

3) EVGA nVidia GeForce GTX 1070 FTW Gaming ACX 3.0

4) EVGA nVidia GeForce GTX 1070 SC Gaming ACX 3.0

For gaming?

Intel Core i5 6402P - RM 707
Gigabyte H110M-DS2 (D4) - RM 276
Kingston 8GB DDR4 2133MHz Value RAM - RM 151
Gigabyte RX470 4GB GDDR5 G1 Gaming - RM 999
WD Blue 1TB HDD - RM 209
FSP Hexa+ 550W - RM 188
Tecware Alpha - RM 199

Total: RM 2729 (ETech price inclusive of GST)
HIS is not widely available in Malaysia that's why it is a bit "underrated" here.

Yes, you can even use adapter/converter if the GPU doesn't have HDMI port, i.e. DVI to HDMI adapter.
Asus Strix OC is more expensive than EVGA FTW, same goes to clock speed and memory speed, your call.

Since you put these 2 cards in your consideration list, then I don't think budget would be an issue anymore (few hundred more expensive than the other brands), so just pick the one you prefer (warranty, after sales services, design, aesthetic purpose like theme/color etc).
AFAIK, Idealtech, DotaTech, ETech they all do have Maybank installment plan, interest rate might apply though.

Intel Core i5 6500 - RM 835
Gigabyte H170-HD3 (D4) - RM 446
Kingston 8GB DDR4 2133MHz Value RAM - RM 151
Palit GTX1060 6GB GDDR5 Super Jetstream - RM 1265
Samsung 750 EVO 250GB SSD - RM 315
WD Blue 1TB HDD - RM 209
Superflower Leadex Gold 550W - RM 409
Phanteks Eclipse P400S - RM 349
BenQ GW2470H - RM 469

Total: RM 4448 (ETech price inclusive of GST)

Different color is having different price for the casing, I am using the base price as reference.

Your budget can fit GTX1070 (Palit Dual Fan, RM 1899) actually but you need to drop the SSD to cover up the money for it.
Better cooling + quieter, this is hard to please 

The default fan curve is quiet (70% RPM at 70C only  ) but cooling isn't that good compared to self-modified fan curve, but of course that's gonna create more audible sound, I am willing to exchange for more performance with the audible sound though since the music sound from my speaker will cover up the sound of the hardware eventually.

Yes other components will be hotter but that's fine for me, I have been on this setup for roughly 2 years last time and temperature was well within the safe range.

Yep, previous build (Air 240), current one is exhaust (Phanteks Evolv ITX).