Intel Core i5 6500 - RM 835
Gigabyte B150M-D3H (D4) - RM 379
Corsair 8GB DDR4 2133MHz Value RAM - RM 130
Palit GTX970 4GB GDDR5 Jetstream - RM 1369
Kingston SSDNow UV400 120GB SSD - RM 153
WD Blue 1TB HDD - RM 209
TP-LINK TL-WN722N USB WiFi Adapter - RM 45
Tecware Alpha - RM 199

Total: RM 3319 (ETech price inclusive of GST)

You can consider the new RX480 also, but not with the reference card at the moment (wait for non-reference card) and AMD to issue a fix to the power overdraw from PCIe slot.

Not recommended to get any GTX970 with price tag > 1.4k now because by just adding another RM 600, you can get the new GTX1070 at ~60% performance improvement over the old GTX970.

If your WiFi router supports dual band (2.4GHz and 5GHz), please get a dual band USB WiFi adapter or PCIe WiFi adapter (more reliable but expensive).

i5 6500 is good enough to yield a solid performance in current games, going from 6500 to 6600 won't give significant boost, the price/performance ratio isn't good.

Only Z170 series mobo can utilize RAM speed of > 2133MHz, so if you get a 2400MHz/2666MHz (or higher) RAM, it will be downclocked to 2133MHz automatically by the mobo, that's because the highest speed supported on H110/B150/H170 is just 2133MHz (the base clock of DDR4 RAM), so there isn't a point to get "performance" RAM when you are going to get a non-Z170 mobo unless the price between the value RAM and "performance" RAM is very close.

8GB x 2 vs 16GB x 1, the former one will run in dual channel mode, which means it will be slightly faster than the latter one, but the difference is hard to notice in real life usage, I recommend you to get 8GB x 2 instead to run them in dual channel mode since the mobo listed above comes with 4 RAM slots (not limited by the amount of RAM slots like those lower end mobo), 8GB x 2 is also slightly cheaper than 16GB x 1 at the moment as well.

You can swap to RX480 but please wait for non-reference model of RX480 instead, reference RX480 runs hotter due to the not-so-efficient blower cooler and possibly a 8 pin PCIe power connector instead of the stock 6 pin PCIe power connector for better overclocking (and fix the PCIe power overdraw issue) 

256GB SSD, yes you can but I think you need to increase your budget for this, just make sure you will have enough storage space if you remove the 1TB HDD, 256GB can be fully filled in just matter of time 

Tecware Alpha comes with 3 casing fans which provide more airflow than other case that is priced at similar price point, airflow is ok, I've built few rigs with this case, temperature isn't a major issue TBH (feedback from actual users), noise level is within acceptable range.

Manta is a mITX case while S340 is an ATX mid tower case, both are under different form factor.

Manta is expensive, one of the most expensive mITX cases out there in Malaysia, this will increase the total cost needed to build a rig.

If you were to spend RM 574 for a B150 mobo, I suggest you to go for H170 instead, RM 574 for a B150 is seriously overpriced (oh well almost all Asus products are overpriced in Malaysia due to its premium status), H170 with more features offered are far more valuable in terms of price/performance.

CPU cooler supported depends on the clearance available, usually mITX case comes with limited amount of space, so you need to make sure the 3rd party CPU cooler that you are going to get is able to fit in the case, same goes to the GPU, Manta is a mITX case so you need to check the clearance available before getting the GPU while S340 is a standard ATX size case so the max acceptable length will be much longer than Manta (should support most of the cards in the market).

There are 2 types of CPU cooler (air cooler and liquid cooler), air cooler is far more preferable because it is cheaper and safer than liquid cooler (no need to worry about liquid leakage). For locked CPU (non-overclockable), air cooler is enough because the temperature is very hard to hit the limit before throttle kicks in, liquid cooler will be overkill for your setup, unless you are going for aesthetic purpose.

Just get a single stick of 16GB RAM if you plan to upgrade to 32GB in the future, 16GB DDR4 is available now, no need to get 8GB x 2 anymore for 16GB RAM 

DDR4 based.

ASRock H110M-HDV, less than RM 300, or just use VGA/DVI to HDMI adapter, probably can save a couple of bucks.
The mobo picked is an entry level Z170 so expect the temperature of the VRM to be higher than those mid/high end one, high temperature will reduce the speed that you can get/achieve and stability, I suggest you to get a better board with better onboard heatsink and VRM counts/design.

The RAM is somehow overpriced, I know Idealtech doesn't carry other brand other than GSKill so you are stuck with its expensive RAM price, Corsair Vengeance LPX 16GB 3000MHz is just around RM 400 only, that's roughly RM 100 difference and you get extra 600MHz native RAM speed with the Corsair Vengeance.

R1 Ultimate can't fit in S340, u can consider water cooling or H7 in S340 casing.