The Ryzen 3000 & 5000 series "Sweet Spot" for RAM Speed is 3600Mhz. The Sweet Spot is where the processor's performance will be at its best for the RAM that is installed.
The "Sweet Spot" for the 2000 series processors is 3200Mhz.
You can install higher speeds of RAM if your Motherboard supports Overclocking to higher speeds. But the performance wouldn't increase that much.
Comparing your previous Ryzen 5 2600 to your new Ryzen 9 5950x:
Ryzen 2600: Maximum Operating Temperature is 95c and its TDP Rating for CPU Coolers is 65 Watts.
Ryzen 5950x: Maximum Operating Temperature is 90c and its TDP Rating for CPU Coolers is 105 Watts.
The 5950x is a hotter processor but with a lower Maximum Operating Temperature. So a high quality AIO CPU Cooler will be needed or High Quality Air CPU Cooler to maintain the processor from overheating and going over 90c.
My opinion is you should find a CPU Cooler that will keep the processor's temperature about 10 degrees lower than the Maximum Operating Temperature to be on the safe side.
The processor is engineered to run at 90c without any issues and before it starts to throttle or slow down. But if you keep the temperature at or below 80c and if the processor should run hotter for any reason than you have a 10 degree safety range to find out why it is running hotter than usual.