I can't answer the DirectX question.
When SFC fails to fix corrupt files the next step is DISM. See the following:
Fixing “Weird Issues” under Windows 8 or Windows 10 Using the System File Checker (SFC) and Deployment Imaging Servicing and Management (DISM)
If you are having "weird problems" with any Windows system, the first thing you should do is to run the System File Checker (SFC). Open a Command Prompt window using the "Run as Administrator" option. The easiest way to do this is to hit the Windows Key, immediately enter the text “Command Prompt” and getting the Command Prompt desktop app returned as the first item. Gain focus on it and bring up the context menu either via right click or hitting the menu/applications key [if your machine has one] or Shift+F10 if it does not then selecting “Run as administrator” from the context menu that appears. Once that elevated command prompt window is opened, enter:
When it's finished look at its output to see if it found any corrupt files and whether it was able to fix them.
If SFC reports that it was unable to fix something, on Windows 8 and Windows 10 systems it's also worth running the following command, also in a Command Prompt window that's been opened with "Run as Adminstrator":
DISM /Online /Cleanup-Image /RestoreHealth
DISM should be able to fix errors that SFC may not be able to fix. If you wish to be really thorough, after running DISM, and presuming it reports that all has been fixed, shutdown and restart your machine and run SFC one final time. The SFC result should be clean.