the top of this thread says to change new models to this:
however I don't have a '4e81' entry in my file - am I supposed to add the 4e81 entry?
No need, just change your file to this to clock to 400Mhz:
package 'cgminer'
config 'asic-freq' 'default'
option 'freq_value' '4f81' #400M
option 'chip_freq' '400'
option 'timeout' '35'
#option 'freq_value' '4d81' #350M
#option 'chip_freq' '350'
#option 'timeout' '40'
#option 'freq_value' '4c81' #325M
#option 'chip_freq' '325'
#option 'timeout' '40'
#option 'freq_value' '0b81' #300M
#option 'chip_freq' '300'
#option 'timeout' '45'
#option 'freq_value' '0981' #250M
#option 'chip_freq' '250'
#option 'timeout' '55'
#option 'freq_value' '0781' #200M
#option 'chip_freq' '200'
#option 'timeout' '70'
#option 'freq_value' '4f02' #193M
#option 'chip_freq' '193'
#option 'timeout' '70'
Just uncomment the 400 setting and comment out the 350 settings
