Just throwing this out early in the discussion.
If you've had it for "several years", don't forget you have a small battery on your motherboard that may be dead. This keeps your BIOS memory active and if it goes dead, you need to replace it.
If after making adjustments you notice nothing is being saved by your BIOS, you might have an "easy" solution at hand.
Not saying this is definitively your issue, but keep it in mind, just in case.
Gentle