If you are using PHP as FastCGI with IIS you should use the Non-Thread Safe (NTS) versions of PHP.
Please use the Apache builds provided by Apache Lounge. They provide VC9, VC11 and VC14 builds of Apache for x86 and x64. We use their binaries to build the Apache SAPIs.
If you are using PHP as module with Apache builds from apache.org (not recommended) you need to use the older VC6 versions of PHP compiled with the legacy Visual Studio 6 compiler. Do NOT use VC9+ versions of PHP with the apache.org binaries.
With Apache you have to use the Thread Safe (TS) versions of PHP.
TS and NTS
TS refers to multithread capable builds. NTS refers to single thread only builds. Use case for TS binaries involves interaction with a multithreaded SAPI and PHP loaded as a module into a web server. For NTS binaries the widespread use case is interaction with a web server through the FastCGI protocol, utilizing no multithreading (but also for example CLI).