Do you have system fan on chassis?
You can try to open chassis shell to make sure this situation is caused by thermal issue
If it is workable that you can add one system fan for it
You mean you want to see device temperature under O.S mode or enter BIOS to check thermal monitor
If you want to enter BIOS, the most default hot-key is "Del" or "F2"
If you want to see it under O.S. that you can install Sandra2007 to see it.
But all motherboard just provide CPU , System temperature value. And every board maker design is different that you may not get right value.