If installing PHP 5.6 on IIS 8.5 (I used the Web Platform Installer on Server 2012 R2) you will see an error (if you run php-cgi.exe directly) along the lines of:
Cannot find MSVCR110.dll
To resolve this, download x64_msvcr110 and place it in:
That should do it, if not, download x32_msvcr110 and place it in:
You shouldn’t need to reboot it either.