If you want the performance, rather get a 4 x 4GB kit as opposed to a 2 x 8GB kit, unless you plan on going 32GB in the future.
Let me try to explain RAM channels as simply as possible.
Depending on your Motherboard and CPU (This applies across the board for Intel/AMD as well as Laptop/Desktop/Server) your memory mode can be (1) Single Channel (2) Dual Channel (3) Triple Channel (4) Quad Channel (5) Flex
Single mode can also be called asymmetic mode and is used when only one DIMM is installed or when the memory capacities of more than one DIMM are unequal (very important that)
Dual-channel (interleaved) mode higher memory throughput and is enabled when the memory capacities of both DIMM channels are equal. So if your motherboard has 4 DIMM slots with slots 1 & 2 in Channel A and slots 3 & 4 in channel B. You can run 2 x 2GB modules in Channel A's slots and 2 x 8 GB is channel B's slot.
VERY IMPORTANT : To achieve dual-channel mode your memory modules need to be the exact same size per channel, however the slowest DIMM module populated in the system decides memory channel speed. Yes, SYSTEM, read that again.
Triple-channel interleaving reduces overall memory latency by accessing the DIMM memory sequentially. Data is spread through the memory modules in an alternating pattern.
Flex mode : This mode results in both dual and single-channel operation across the whole of DRAM memory.
Theoretically running Dual-Channel mode should allow faster transfer of data between the CPU and memory up to the maximum speed of the FSB (Front-Side bus); Slow(ish) FSB means your super fast overclocked gaming RAM might never reach its full potential.
so i bought the following:
PC Case: [BLACK] Evetech FROZR ATX Gaming Case With 4x LED Fans
Power Supply: 500W 80+ High Performance Power Supply
Processor: Intel Core i5-7500 (3.4GHz, 6MB Cache, 4x Cores, 3.8GHz Turbo)
Heatsink & CPU Fan: Antec A30 CPU Cooler With Silent LED Fan
Motherboard: MSI B250 Gaming Pro Carbon DDR4 USB 3.1 Motherboard
Memory: 12GB DDR4 2400Mhz High Performance Gaming RAM
Graphics Card: MSI GeForce GTX 1070 GAMING X OC 8GB GDDR5 Card -
Sound Card: Integrated 8 Channel HD Audio -
Primary Hard Drive: 250GB Ultra-Fast SSD Upto 500MB/s+ Speed Solid State Drive
Secondary Hard Drive: 1TB WD Blue 7200RPM 64MB Cache HDD
LCD Monitor: [Special] Samsung 22" Slim 1920x1080 Full HD LED Monitor
Keyboard & Mouse Combo: Redragon S101 Gaming Keyboard & Mouse Combo
Mouse Pad: Redragon ARCHELON M Gaming Mousepad
Speakers: Creative A250 2.1 Stereo Speaker System
Warranty: 2 Years Return To Base (1st yr. Parts & Labour, 2nd yr. Labour only) - Included
and i must say its amazing i gave it a good test on battlefield 1 last night on ultra settings.
and i got smooth gmaeplay with Frames well over 70fps. its amazing! thank you for all your help