HELP!! I flashed the bios to 20130821 last night and now its 20x worse!! Runs at 100ghs for about 30 seconds before dropping to 5ghs - 20ghs erratically. Left it for a few hours and no better. Tried a couple of versions in between with same results before flashing back to original backup and now that's fucked too

Any suggestions? this is killing me!!!
Yours is a batch #3, it's probably throttling because of temps as the sensors have changed so the default temps are too low
In more options try
--real-quiet --avalon-auto --avalon-fan 100 --avalon-temp 70 --avalon-cutoff 90