As I suspected, the temperatures the Speccy included were way way way off.
As for the original problem, have you checked in the Power Settings to see if there have been any changes made there?
Since this is a Windows 10 problem you may benefit by running sfc /scannow.
sfc /scannow for Windows 10
Please run System File Checker.
The sfc /scannow command scans all protected system files and replaces corrupted and incorrect versions with correct Microsoft versions.
Important: There will be a short message at the end of the scan informing you of the results. If you receive the message "no integrity violations were found" you don't need to do anything else, no corrupt files were found. You should watch the scan to see the results at the end of the scan.
This needs to be run using an Administrator account.
You will need to open the Command Prompt to run the sfc /scannow. The easiest way to do this is to press the Windows key and the X key. A menu will open with the option Command Prompt (Admin), click on this. This will open the Command Prompt.
Important: Depending on which version of Windows 10 you are using the option in the menu for Command Prompt (Admin) may have been replaced with Windows PowerShell (Admin). The command used here needs to be run from the Command Prompt (Admin).
To switch the option back from Windows PowerShell (Admin) open the start menu, tap/click on Settings, then select Personalization, then Taskbar.
Under Taskbar you will see the option Replace Command Prompt with Windows PowerShell in the menu when I right-click the start button or press Window key + X key. Move the switch so that Command Prompt (Amin) is on.
If you are prompted for an administrator password or for a confirmation, enter the password, or click Allow.
Copy and paste the command below in the Command Prompt, then press Enter.
This scan will take a while to run, please do not abort the scan as this can result in damage to the operating system.
If integrity issues are found in the scan please post the CBS log using the instructions below.
To find sfc /scannow log click/tap on File Explorer, select the drive which Windows is installed on (this usually is the C: drive), click/tap on Windows, then Logs, then CBS. If there are more than one log you can identify the log you want by the date and time it was run.
Copy and paste the log at the host website I've suggested below.
This log usually is very large, for this reason you should use a host website like Dropbox to post the log. You can start a free 30 day trial. Once you have loaded the log at Dropbox post a link to the website.