How many people have upgraded the S4 firmware to: initramfs.bin.SD-20141016.tar.gz from the bitmain website?
I only ask because mine is still running on the factory firmware no problem with difficulty manually set, so I'm kind of wondering if I should bother with the upgrade.
I upgraded all of my S4's to this firmware and gained at least 5% hashing speed on the pool. I also set difficulty to 2048. 225 Mhz 0725 volts . They are all hashing at least 2200 and are stable meaning I don't have to hard reboot them every day for crashed chips or reduced hashing speeds.
Maybe I need to upgrade my firmware. When S4 hashing rate drop to below 1500 Gh/s, my pool with Ghash.IO goes to zero. I had difficulty set to 2048 manually.