Stuttering is mostly caused by operator error, ex: bad hardware choice , OEM, bad configuration, bad driver install
stop using programs such as game booster, do everything manually.
EDIT: Awfully bad thing that your mouse refresh got 125mhz, it's driver error and it should have been set to 500mhz default.
Reinstallation of windows is mostly a waste of time inexperienced users always take lightly, if you didn't have customizations in the first place you probably didn't lose a lot of work.
Most of issues if not all PC issues i did had , reinstallation is not needed. I used to do a reinstall when i didn't knew a fix, nowadays i know how to fix pretty much anything and if there's no fix , i research and find a fix my self , but i do not get any critical situations either since of the experience i already prevent it from happening before it does.
EDIT: A crash took out all HDD info ... how the heck did you do that ?
More RAM won't fix an issue like stuttering UNLESS you have researched and identified that you are low on memory. This is mostly not practically doable with pagefile enabled, you have to disable the pagefile and then see the COMMIT readings in task manager.
You bought another RAM, and you just "put it in there" there is no surprise that you have issues when you don't configure the RAM, i don't suppose you got identical sticks with same version and voltage specification even if it's the same brand and same MHZ , it might have different clocks - plus you never told any specs whatsoever.