Re: PHP - only seems to run one instance?

Try these values:
[opcache]
opcache.memory_consumption=512
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=8000
opcache.revalidate_freq=240
opcache.fast_shutdown=1
opcache.enable_cli=0
opcache.enable_file_override=1

Disable this one for nginx,
multi_accept on;