Please keep the forum rules in mind when you post so that this forum remains civil and everyone can participate, contribute and learn.
No one said it could be a PC case airflow issue.
If you felt the OP had an issue with his PC case not having sufficient airflow - even though he presented no information that suggested this to be the situation, there are useful ways to alert him of a potential problem without making statements that may not be true and that could be confusing. You could suggest that he check the airflow thru his case if he is seeing high CPU/GPU or mobo temps. That way you're not sending him chasing problems he has not indicated exist.
If he doesn't have higher than normal CPU/GPU or mobo temps then there would be no need to for him to pursue that possibility. Stating that lack of PC case airflow IS the problem when you have no information to reach this conclusion is purely speculation and should be stated as such not as a fact as you did.
The above suggestion is practical decorum and has nothing to do with one's opinion. If you were seeking help here you wouldn't want someone sending you off in a direction looking for a problem that doesn't exist and was never mentioned or suggested by the information you posted.
Building a reliable PC involves more than just assembling the parts. You need to be able to configure all of the BIOS settings appropriately. This can be quite involved and frustrating as it can require a lot of trial and error with stress testing. It is however often the only means to get a 100% reliable PC.