I've run into issues of trying to upgrade my wamp server. Still running 2.0. I can't find a smooth way to upgrade without breaking everything.
So in the meantime i wanted to just use a newer version of php with my current wamp server. I thought i could download the latest version of the windows bianary and then put it in the bin folder (c:wamp\bin\php) of wamp server and restart. But i don't see it as an option to choose.