that motherboard has a funky memory layout

normally they are labeled 1-4 not 4 2 3 1. and then you populate the odds or even slots. this leaves a gap in between and helps with cooling (what little they need)

Follow what the motherboad manual says for the memory slots, 1 and 3 or 2 and 4.

Secondly your sticks might be 2400MHz but unless you enable DOCP in the bios they will run at 2400MHz. you can see this by the 1200MHz in CPU-Z (DDR, Double Data Rate so its actually 2400MHz)

DOCP could be called EOCP on gigabyte. turn this on and you will get another 800MHz bump in memory speed to 3200MHz. its done from within the bios. on my asus board its on the main screen when you get into the bios.

your image of the memory tab shows they are in single channel. move one stick then check is it says dual channel.

I have the 390z mobo using slot 1 and 3 and can confirm with CPUz that it is running in dual channel

https://www.youtube.com/watch?v=suAIR4XtLgI

I also used this video linked from cpu benchmark as a guide to change my RAM frequency in BIOS........ as I’m not very literate with computer stuff (although I did build my last two PCs) I found it easy to follow.

kiwis:

 

That's what the manual says,

 

 

But this confuses me.. It's literally underneath each other in this order. 

 

 

OK I can see why that is confusing. I believe the second image is incorrect, and the headers across the top should read DDR4_, DDR4_3, DDR4_2, DDR4_1.

If you have only two modules, put them in slots 1 and 3.

Cheers

at the end of the day you can confirm you are in dual channel mode in CPU-Z. if its not then change the slots.

For some reason gigabyte have called it XMP, check out page 25 of the manual set it to profile one. and you should see the ram speed increase.

1024kb: Also, desktop DDR4 has this thing that I think is dumb. Desktop DDR4 RAM is generally all locked to 2133MHz, even the higher-rated RAM. Whatever MHz number is printed on the box is irrelevant without setting the frequency in BIOS. Yes, you actually gotta look at the speed rating of your sticks & enter that number manually in BIOS, overclocking it from the entry-level speed (2133MHz) for DDR4.

no you dont,

mine showed as 2666mhz, i set docp and it went to 3200mhz which is its rated speed. 2 clicks done.

So I guess a question is. 

Do I trust the manual or CPU-Z. The board itself is marked as per the manual as far as order goes.

I've set my BIOS to profile 1. This is what CPU-Z shows now. Is this as expected?

Looks better.

Dual channel and 1600MHz speed, which means its running at 3200MHz.

SpartanVXL: Massive amounts of confusion here. OP you got it right now but so many people reading the table incorrectly. Yes Gigabyte make it confusing by alternating the slot numbers but please read their docs.

Dual channel by definition is ‘two channels’

The table specifically lays out that:

Channel A: slot 2, slot 4
Channel B: slot 1, slot 3

If you want DUAL channel you need something in BOTH channels. OP got it right with slot 1 and slot 2 (or slot 3 and slot 4).

Everyone who said slot 1&3 misread the docs and would get single-channel only.

Cheers for the clarity. I was still unsure why it was showing dual in CPU-Z and working better yet being in contrary to the manual. But this clarifies it nicely. 

Ironically, my original question never got answered though. 

To increase my RAM from 16GB to 32GB (debatable if an improvement will be noticeable/worthwhile). I need to get another 2 sticks of 3200Mhz 8GB ram?

Something like this

https://www.pbtech.co.nz/product/MEMKHX37006/HyperX-Fury-16GB-RAM-2-x-8GB-DDR4-3200MHz-CL16-135

There's not point getting 2666Mhz or 3600Mhz or 2X 16GB ram etc is there?

Try and get the same as whats in there if you can.

but its likely going to make little to no difference.

kiwis:

 

I've got 16GB of RAM on my machine and am looking to increase this to see if I can get a bit of performance improvement from a few different games.

 

I have a B450 Pro motherboard, and looking at CPU-Z I've got two sticks (slots 3 & 4 in use) . I assume I have another two slots in there? (I've not opened it up yet).

 

What's the logic with RAM again, I can only equal what I have as anything bigger will only work as hard as the weakest list? So a 16GB won't double it if I currently have two 8gb will it? 

 

I think I'm better off getting another 2x 8GB DDR4 ram to make 34GB in total? - please correct me if I'm wrong.

 

Also, what's the best affordable (cheap) DDR4 8GB ram out there). I don't want to sink a heap of money in it as I may not get much improvement at all. 

 

 

Give us a full rundown of your computer setup, what games you are hoping to get more performance out of as well as what you expect it to run like and then we might be able to comment if adding RAM will help or not.

There were some obvious setup issues in your rig which you have now fixed so now you should be able to get a picture of how its running. 

It would also help to run something like hwinfo64 while you game and record some of the info that captures to see how your system is running overall.