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.
Fortunately, Intel is relatively tolerant of mismatched ram.
This is more difficult when more sticks are involved.
Ram must be matched for proper operation.
What is your plan B if the addition does not work properly?
To avoid possible problems,
I suggest you buy a 2 x 16gb kit and sell the old ram or keep it as a spare.
You can sometimes compensate for errors by increasing the ram voltage in the motherboard bios