OK, so one of my new S3 machines is hashing at 402.75Gh/s. Frequency is 218.75. One of the strings (if that is the word) is showing oooooxo-. Rebooting through the web interface, or physically power cycling doesn't fix it. Reading through this thread the suggestions are

1) Downclock to 212
2) Update firmware
3) Dismantle and replace thermal compound

Which of these is most likely to fix the hashing? Is there anything else I should try?