When in, you'll have to fill in login credentials.
Now logged in, type in the following:
cd /etc/config
You are now in config folder.
Now type:
vi asic-freq
When in the file hit:
i
This will allow you to edit the file.
Now you can see lines that start with '#'.
Remove the hashtags of which clockrate you want and place hashtags at those you dont want.
For example:
#option 'freq_value' '0780' #400M
#option 'chip_freq' '350'
#option 'timeout' '36'
option 'freq_value' '4d81' #350M
option 'chip_freq' '400'
option 'timeout' '36'
....
Remove hashtags from the 400M options and place them infront of the 350M options.
Now you hit ESC and type:
wq!
exit
Now reboot and done.
Ofcourse you can change the option values.
I have mine to:
option 'freq_value' '4d81' #400M
option 'chip_freq' '393'
option 'timeout' '37'
This way it's better for the chips and uses about 50W less power.