120GB SSD for OS installation (will take around 25GB for fresh Windows 10 installation + Windows Update).
HDD for games files/music/movie/document etc, please bear in mind that the size of the games is getting bigger and bigger nowadays, so your 500GB (several) might not enough in the future.

Intel Core i7 6700 - RM 1289
MSI B150M Pro-DH (D4) - RM 346
Corsair 16GB (8GB x 2) DDR4 2133MHz Value RAM - RM 260
Palit GTX1070 8GB GDDR5 Jetstream - RM 1999
Corsair Carbide 88R - RM 226

Total: RM 4120 (ETech price inclusive of GST)

For 5k build, you can go for OC build, but performance gain is small or non-existent in gaming because most of the games are still based on single threaded operation 

You can also bump the GTX1070 to GTX1080 (+ 1k for Palit Jetstream model) or allocate it for your monitor instead, 1k can get a 1080p 144Hz already, but yea I know you wanted to get Dell S/U series monitor, just a suggestion here, 144Hz > IPS for FPS games  

Do bear in mind that SLI/CF is not supported by all games, you will end up running single GPU only if SLI/CF support is missing, the scaling for SLI/CF is still poor nowadays, meaning you won't get the double performance of single card, getting a more powerful single card is better than running 2 weaker cards at SLI/CF.

To SLI/CF, you need at least 2 PCIe 3.0 x8 slots running at parallel, the cheapest one is around RM 700 and that's ATX size (Gigabyte Z170XP-SLI/Asus Z170 Pro Gaming etc.), if you are sticking to mATX then there is only 1 option available currently in local market which is the expensive Asus Maximus VIII Gene (more than 1k). mATX casing comes with at least 4 PCIe expansion slots but you need to check the height of the GPU that you are going to get because some mATX mobo/casing only allow GPU with the height of 2 expansion slots for SLI/CF.

As for PSU requirements, true power 600W PSU should be enough for RX 480 running on CF, please wait for official reviews in the coming days for official data and power draw from the wall to determine whether your current PSU is enough for this or not.

You can always take advantage of the GPU by utilizing sumpersampling technology (DSR or VSR) to get a more detailed image on 1080p, the details of supersampling technology can be found in few previous posts.

You can get Acer XB240H with 1k budget, RX 480 is an AMD product so you need a FreeSync monitor if you want GSync equivalent feature on AMD card, AOC G2460PF is one of the examples, around 1.2k+/-.

SFF (mITX) only comes with 1 PCIe slot, so SLI/CF isn't an option. For console-like casing, you can look for Silverstone RVZ01/FTZ01 etc.

RX 480 is packing with GTX980-like performance (estimated) while GTX1070 is packing the performance of Titan X (+ extra 10% faster), they are on different tiers.

1080p FreeSync is cheaper, if you go for Nvidia path then getting a 2K QHD or 4K UHD GSync monitor is more worth than a 1080p GSync monitor because the price of the only one 1080p GSync (Acer XB241H) monitor in Malaysia is too close to his bigger brothers, XB281HK (4K UHD 60Hz TN, RM 2489), XB271HU (2K QHD 165Hz IPS, RM 3189).

You get 2 extra USB ports (depends on manufacturer whether to implement it or not), full x16 PCIe configuration speed, RAID support by going from B150 to H170.

RX480 is more like a FHD card instead of QHD card, I recommend you to stay with 1080p, QHD IPS isn't cheap anyway, the cheapest one is around 1.5k but that's 25", QHD is best viewed on 27" and above to match the PPI.

B150 also has x16 on its PCIe slot, the one I meant is for PCH setup.

The viewing angle on TN display is poor if compared with IPS, but if you aren't always viewing the display from the side then this is fine, color quality on TN is fine too if you view from the front, everything on TN looks bad only if you are viewing from the side, what you get on TN is much higher refresh rate at cheaper price tag. If you go for Dell S2316H/S2415H then you need to take note that it comes with a glossy screen, meaning you will see your reflection when you are under a bright light source.

Silverstone SG13 is a mITX case while SG11 supports mATX and mITX board, stock cooler won't be an issue for SFF case unless you plan to use a 3rd party cooler where you will be restricted to low profile 3rd party cooler only like Cryorig C7 or AIO liquid cooler (if supported).

Asus H170M-Plus is a better choice if you are aiming to get those premium features over ASRock, it comes with native USB Type-C port too which is great if you have any gadget using this type of port for fast charging support, the price difference between them is small, Asus one is definitely a better pick here.

FHD, QHD, UHD all available but we have limited choice in Malaysia.

ViewSonic VX2457-mhd 24" 1080p 60Hz TN - RM 699
AOC G2460VQ6 24" 1080p 60Hz TN - RM 799
AOC G2778VQ 27" 1080p 60Hz TN - RM 989
AOC G2460PF 24" 1080p 144Hz TN - RM 1139
Samsung U28E590DS 28" 4K UHD 60Hz TN - RM 1899
BenQ XL2730Z 27" 2K QHD 144Hz TN - RM 3189
BenQ XR3501 35" 21:9 1080p 144Hz VA - RM 3999

Actually most of them are doing the same thing/job, which is trying to protect the mobo from frying up when excessive voltage is detected/lightning strike etc, some provide basic protections (lower end mobo) only which protect the important components such as CPU, RAM etc, some provide LAN protection, capacitor/VRM protection etc.

USB Type-C is still not widely used yet (mostly smartphones now), so some manufacturers opt to skip it and use the slot for other connector instead and Skylake doesn't support USB 3.1 officially (will be supported in Kaby Lake), manufacturers have to use their own controller for USB 3.1 port that's why some of them have limitation.

Dell UltraSharp is more premium and supports pivoting (portrait mode), the panel used on U2414H is also better than R241Y.

The price you listed is quite cheap, it is selling over RM 620 for R241Y and RM 920 for U2414H (RRP is RM 1065) from what I've seen here on the Internet 

If you need pivot support like what I do then you gonna go for U2414H (or its successor U2417H), it should be the cheapest premium IPS + ultra thin monitor that supports pivoting nowadays.

Portrait mode is very useful if you are running multi-monitors setup and have limited amount of space, you can get a longer view of web pages as well, just like QHD/UHD screen.

If RM 300 isn't too much for you then I will recommend U2414H over other monitors, I have one and it served me very well and I even upgraded to its successor U2417H to show my support to Dell UltraSharp series