solve "maximum number of descriptors" problem

we're using nginx under windows 2012 server, package WT-NMP.
load is getting higher and today we're started getting this errors in error log

2014/02/20 16:21:29 [error] 4744#712: *94523 maximum number of descriptors supported by select() is 1024 while connecting to upstream, client: 82.145.222.30, server: someserver.ru, request: "GET /feed/index.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9163", host: "www.someserver.ru"

most of clients are getting pages normally, but some (I think 5%) get error 500 or "can't connect"

we've worker_processes 2 (increasing doesn't help)
worker_connections 16384;

we've phpfarm with 160 processes
upstream php_farm {
server 127.0.0.1:9001 weight=1 max_fails=3 fail_timeout=15s;
server 127.0.0.1:9002 weight=1 max_fails=3 fail_timeout=15s;
server 127.0.0.1:9003 weight=1 max_fails=3 fail_timeout=15s;
...

I've searched the web and some people say you can change file handle limit in config.nt, I've tried to put
files=4096
in c:\windows\system32\config.nt
but nothing changed.

please help to solve this error, so all our clients can get pages.