Here are my configuration files

ssl.conf

# HTTPS server
#
server {
listen       443 ssl;
server_name  api.domain.com;
error_log    /var/log/nginx/api.error.log;

location / {
root /var/www/api.domain.com;
index index.html index.php index.php;
try_files $uri $uri/ /index.php?$args;
}

ssl                  on;
ssl_certificate      /etc/nginx/api.domain.com.crt;
ssl_certificate_key  /etc/nginx/api.domain.com.key;

ssl_session_timeout  5m;

ssl_protocols  SSLv2 SSLv3 TLSv1;
ssl_ciphers  HIGH:!aNULL:!MD5;
ssl_prefer_server_ciphers   on;

# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
location ~ \.php$ {
    # root  html;
    fastcgi_pass   127.0.0.1:9000;
    fastcgi_index  index.php;
    fastcgi_split_path_info ^(.+\.php)(.*)$;
    fastcgi_param SCRIPT_FILENAME /var/www/api.domain.com$fastcgi_script_name;
    fastcgi_param HTTPS on;
    include fastcgi_params;
    }

location ~ /\.ht {
    deny  all;
}

}

nginx.conf

user              nginx;
worker_processes  1;

error_log  /var/log/nginx/error.log;

pid        /var/run/nginx.pid;

events {
worker_connections  1024;
}

http {
include       /etc/nginx/mime.types;
default_type  application/octet-stream;

log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for"';

access_log  /var/log/nginx/access.log  main;

sendfile        on;
#tcp_nopush     on;

#keepalive_timeout  0;
keepalive_timeout  65;

gzip  on;
include /etc/nginx/conf.d/*.conf;

}

I have a server running on port 80 that runs with no issues. As soon as I turn on this api server running on ssl, it works for about a minute and then crashes and gives a 504 Gateway Time-out.

Running nginx/1.2.3