DDR4 RAM guide

So, I’m currently running this memory
2 x DDR4 G.Skill RipJaws 4, 4GB,F4-2800C16Q-16GRK
which totals 8GB...
I’m looking to bump that up to 16GB, and now I’m stuck wondering if it’s smarter to just grab a fresh 2x8GB kit from a reliable brand, or perhaps go with a 4x4GB setup... or, given that I can't find these exact sticks anywhere locally in my neck of the woods, maybe I should just pick up two more 4GB sticks from a different manufacturer, like
Corsair Vengeance LPX

Thanks

Just pick up two more sticks from a different brand then (ideally matching the CL, clock speed, and voltage).

What’s the actual distinction between the rated response time and what you get in real-world performance...
Let's look at my current setup for context.
Series Corsair Vengeance LPX
Memory Type DDR4
Storage Capacity 16GB (4GBx4)
Dual-Channel kit Dual-Channel kit
Tested Speed 2800MHz
Response Time 16-16-16-36-2N
Standard Voltage 1.20v
Registered/Unbuffered Unbuffered
Error Checking Non-ECC
JEDEC Standard 2133MHz
SPD Voltage 1.20v
Fan lncluded No
Height 40 mm / 1.58 inch
Lifetime Warranty Lifetime Warranty
Features Overclocking Profile Ready

Now, comparing this to another set
Technical Specifications

Storage Capacity: 8GB (2x4GB)
Speed: 2800MHz
Response Time: 16-18-18-36
Voltage: 1.2V

Format: Unbuffered DIMM
Pin Out: 288 Pin
Overclocking Profile
Aluminum Heat Sink: Anodized Aluminum

--
So the voltage is identical at 1.2V
Both run at 2800MHz
They both claim C16 in the titles, which leads me to assume the latency is the same, yet when I look at the official response times listed on their respective websites, they don't match up at all...

Hey there

I'm looking at upgrading my rig and I'm stuck between two motherboards because of the RAM situation. There's the ASUS ROG, which can handle up to 3200MHz, or the Asus Sabertooth Z170, but that one tops out at 2400MHz. I'm planning on running an i7 6700k. If I go with the ASUS ROG and grab some 3200MHz sticks, would they actually hit 3200MHz? Since the processor itself only supports up to 2400MHz, I'm wondering if it'll even matter.

Maybe you could save a few hundred bucks and just grab the MSI MPG Z790 instead. It supports up to 3800MHz, so it's still top-tier for overclocking and has basically every connector you could ever need. I’d probably just go with 3000MHz RAM too, since they’re $50 cheaper anyway, and honestly, I don't think you'll notice any real difference.

Not trying to be a pedant here, but I might have misspoken earlier. It’s not like I’m insisting on 3200MHz RAM or anything, just wondering about the math. According to the specs for the Intel Core i7 6700K, the max supported RAM speed is capped at 2400MHz. So, if I grab a motherboard that handles up to 3200MHz and pair it with 3200MHz sticks, are they actually going to run at 3200 or am I stuck at 2400?
Because if they just sit there at 2400MHz, I’m leaning toward an ASUS board. I really want to see everything through the case window, you know? But it’s about $30 more expensive. Another thought was the ASUS ROG Maximus VIII Hero.