I wonder if it will be possible to mine anohter profitable coin with GPUS and Randomx with our CPU on the same PC.
Yes it is possible, by running two different instances ( CPU mining and GPU mining)
However, profitability is the issue, depending on your current Electricity cost if its worth it.
specify or allocate resources for your windows system on CPU in order to not freeze
or will it be from the CPU miner settings?
Most mining app has a capability to specify how much/many cpu cores to be used
if not, then this link can help
https://smallbusiness.chron.com/designate-cpu-usage-45952.html