If you have a power limit you might want to try what I have done; you can't use the newest firmware as it changes all the directories. Instead start with 1l1l11ll1ls img:
https://dl.dropboxusercontent.com/u/16075357/bitmain.img.zipthen:
Download Putty if you don't already have it:
http://www.chiark.greenend.org.uk/~sgtatham/putty/download.htmlDefault for S2 is:
SSH LOGIN is root
SSH PASSWORD is admin
Step 1 Open Putty and SSH into your Miner by entering its ip and clicking open
Step 2 Click "YES" on the "Security Alert" that pops up
Step 3 Login with
User: root
Password: admin
Step 4 Type "cd /config" without the quotes
Step 5 Type "vi asic-freq.config" without the quotes
Step 6 Hit the i key to edit the file
Step 7 Scroll the the bottom (with the arrow keys)
You should see many different configurations with #before them. Placing # before a line makes it a comment and not a configuration. Find the configuration without the #'s.
change it to the following
option 'freq_value' '0e06'
option 'chip_freq' '90.62'
option 'timeout' '50'
Step 8 Hit "esc"
then
while holding the shift key type "zz"
Step 9 (IMPORTANT) type "cp asic-freq.config /etc/asic-freq.config"
IF YOU SKIP THIS STEP ALL SETTINGS WILL BE LOST WHEN YOU POWER CYCLE THE MINER
Step 10
Login to the web interface of your miner and go to the miner config tab;
click "save and apply" this will restart cgminer with the new settings
If you have a Kill-a-watt you can confirm power use.
http://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU/ref=sr_1_1?ie=UTF8&qid=1415641355&sr=8-1&keywords=kill+a+wattThere are many different settings you can use but I have tested this configuration and it is stable.
I would mine normally as long as possible before underclocking as it only offers approx 0.18 watt/GH efficiency gain for approx 500 GH loss.
