Your 16 GB of RAM is it 4x4 or 2x8 ?
Need System complete specs, especially the CPU, MOBO, RAM.
Do the following:
1. Check your motherboard manual to see how the paired slots are arranged. Usually they are 1+2 and 3+4, but some boards are weird and do 1+3 and 2+4, or even 1+4 and 2+3. You need to know which one you have.
2. Check which of your RAM sticks is paired with which, do NOT mix them up, and reinstall your double checked RAM pairs into their respective paired slots.
3. Did you buy a 16 GB kit or got 16 GB via 2 8 GB kits ? Sometimes RAM will just not work when its 2 kits, even if the same brand and model.
4. In your bios, you should be able to tell which one of your RAM slots is not reading, or not fully reading your RAM, make a mental or paper note of it.
5. Make sure your mobo actually supports the your RAM at the quantity, speeds or XMP you are trying to run it at. Sometimes boards will support ram, but not at all speeds or at all quantities / configurations.
Now do the following:
Reset BIOS RAM settings to defaults, power down.
Discharge your computer and remove all RAM. Clean them + the slots.
Get only 1 of the sticks, from a slot that was NOT missing/misreading any RAM.
Plug it into a verified good slot closest to the CPU. One of the slots that was NOT misreading, if the closest to the CPU slot is the one that was misreading, then go to the next closest.
Boot up your computer, see if it reads proper amount of off the stick you put in.
Rinse and repeat above for each RAM stick seperately.
This will tell you if any of your RAM is bad. If all your RAM checks out good and your board specs fully support the amount and speeds, then you have a bad slot. If one of your RAM sticks is bad, then you will need to replace the kit. I do not recommend mixing kits, especially on systems with known RAM issues.
If you have the option, for example your kit is 2x8 but you have 4 slots, or your kit is 4x4 and you have 6 or 8 slots, then obviously try the other slot pairs. See if that works. Otherwise, if it turns out to be a bad slot, your only other option is to get a new board.