php upgrade to 5.6 - how do I change the version that nginx is using?

[EdViva]

I have upgraded php to 5.6 in order to get some mailchimp functionality to work, including upgrading to php5.6-fpm. At the moment I have both 5.3.* and 5.6 running but nginx is just using the old version. If i shutdown the service then the sites are not served. I am using perusio's fpm config files. How can I get nginx to use the upgraded version of php-fpm? I am using tcp not unix sockets.

[iryston]

What are the "listen" directives in your 5.3 and 5.6 php-fpm pools?
They should use different ports.
Check if the "server" directive in upstream_phpcgi_tcp.conf is matching to configured pools for corresponding PHP version.