can i mix memory?

[productionsvgs]

i currently have 8gb of 2400 memory in my system it is a ballistix sport LT
i cant find the same module of ram for a good deal anywhere am i able to get a different module like corsair vengeance 8gb 2400?
i am getting more ram because my gpu(1070) and CPU(i5-8400) are bottle necked by it being a smaller amount(was told this by multiple sources i thought 8 would be fine)
i play BO4, league of legends, mortal kombat, and im going to be getting skyrim elder scrolls 6 as well as rainbow 6 siege.
this is my first pc and i am still learning

 

[geofelt]

Ram is sold in kits for a reason.
A motherboard must manage all the ram using the same specs of voltage, cas and speed.
The internal workings are designed for the capacity of the kit.
Ram from the same vendor and part number can be made up of differing manufacturing components over time.
Some motherboards, can be very sensitive to this.
This is more difficult when more sticks are involved.
That is why ram vendors will NOT support ram that is not bought in one kit.

If you do buy more disparate sticks, they must be the same speed, voltage and cas numbers.
Even then your chances of working are less than 100%

What is your plan "B" if the new stick/s do not work?

Sometimes increasing the ram voltage in the bios will make things work.

If you want 16gb, my suggestion is to buy a 2 x 8gb kit that matches your current specs.
Then, try adding in your old 8gb,
If it works, good; you now have extra ram.
If not, sell the old ram or keep it as a spare.