using a MS Iron gaming PC case, it has one fan, the airflow isn't a problem.
one fan in any "gaming" system means that airflow is definitely a problem.
and if this one fan is only the one on the CPU cooler heatsink then it is even more of a problem.
your system would just be recycling the same air which is getting hotter and hotter all the time.
you need to be drawing in a good amount of cooler outside air while also exhausting a significant amount of the heated air to fight the temperature buildup on all components.
was doing stuff with a i5 9400f with a stock cooler and same case and it worked fine but with this cpu and cooler the temps go to 110 degrees Celsius
doing "stuff" normally wouldn't be the same as running any type of demanding games for any amount of time.
any modern AAA games are really stressing the CPU, GPU, RAM, and power supply for the entire time they are running.
and the 7 series 5700X is going to put off much more heat than any i5-*400 model CPU.