I recently purchased some 3200mhz ram, mainly because i wanted to upgrade from 16gb to 32gb, but I thought at the same time it was worth getting a decent speed upgrade. I didn't realise until I installed the ram, that my motherboard only supports a max of 2400mhz. Will the speed difference between 2400 and 3200 make it worth buying a new motherboard, or is it negligible?
For gaming, and considering the rest of your hardware, it may not be worth it if you can not find a good one at a low cost. Especially since they are no longer produced, it can be tricky to source a good one, and for a good price.
Lower timings as much as you can to make up for some performance, then once you upgrade in the future the DDR4-3200 kit can be transferred over and take better advantage.
The benefits of faster RAM are less for Intel. However you are currently missing out on the ability to overclock, upgrading the motherboard would allow overclocking and faster RAM which might be beneficial (you still haven’t listed full pc spec).
However if you are changing RAM and motherboard you probably want to consider upgrading the cpu to a 9700k or Ryzen 3700x.