I would strongly suggest not upgrading to the newest firmware!
(antMiner_S320140811.bin)

Effect on hashrate as reported at pool - 30 mins:



Miner dashboard - 30 minutes:



It changed the frequency to 237.5 according to the new advanced settings tab under miner configuration, but it does not show any frequency on miner stats page (above).

Best speed seen since upgrade: 119.27GH/s

Average speed prior to upgrade: 447.82GH/s (@Freq 225, surprisingly not an option under advanced settings)