This is the php-fastcgi file, /usr/bin/spawn-fcgi -s /tmp/php.sock -M 0666 -C 9 -u nginx -g nginx -U nginx -G nginx -f /usr/bin/php-cgi -P /var/run/fastcgi-php.pid And in this file I didn't restrict parallel connections to 520. Posted at Nginx Forum: http://forum.nginx.org/read.php?2,240989,240994#msg-240994