CPU clocked capped to 800 MHz

There's a 100 MHz clock that is multiplied up and when the CPU is overheated or has other issues, the CPU protects itself by switching to the x8 multiplier.

"When a processor is stuck at the failsafe frequency there are 2 possible issues: bad heat dissipation or power issues.
Now since the CPU voltage is automatically lowered when failsafe occurs you cannot know which of the two issues are causing the failsafe."
- https://forums.tomshardware.com/threads/i5-6500-stuck-at-800mhz-and-8-multiplier.2608009/

-> I DO NOT EXPECT THIS TO BE A BIOS ISSUE GIVEN THE AGE. You didn't write this PC always did this.

It's old enough to have the CPU heatsink compound replaced and while we're in there, do the usual cleaning and fan check. The criteria for fans is "works like new."

1. Try the solution on page 2 of https://forums.tomshardware.com/threads/i5-6500-stuck-at-800mhz-and-8-multiplier.2608009/page-2?view=date
2. See https://forums.tomshardware.com/threads/4670k-stuck-at-800mhz.1749370/ for another area to try.

-> Again, at this age I would do the CPU heatsink work (it's a dollar's worth of compound), clean and fan check.

And yet I found no document on BIOS settings in regard to the external power supply but did find others that write using the next size Dell 90+ Watt adapter is known to cure this.

-> There are too many complaints about the 65 Watt adapter so I'm going to write the 65 Watt adapter is a bad idea.