Good news that both tests passed at least, can you do the following for us please;
Go to Start then to Run/Search
Type in compmgmt.msc and click Enter
On the left side click on Disk Management
On the right side you will see your hard drive.
Now I need you to take an expanded screenshot and attach it to your next reply.
The fact that you have had no trouble while there has been minimal devices attached does suggest that the PSU is causing the issue by being underpowered and so working harder which generates more heat.