I have 4 of them ,only 1 is getting low HW errors and good performance
The rest of them perform like this one : https://gyazo.com/af319f55fa78b0ed11626611e76888b0
with HW errors around 0.03 % or higher
How can I fix this ?
Why do you think that 0.03% is too much? If you remember, previous generations of Bitmain ASIC miners (S2 for example) had way more HW errors, my S2 ran at 0.9%. But at the pool there was about 1+ Th. So did I lose any valuable amount of hashing power? I guess no.
Also I found that my S7 (Batch6) gives many HW errors right after start, it can be up to 3% in first seconds (I saw it once), but take a look at the HWE percentage after 20-30 minutes...
Because at original freq or under it is 0.0000% HW error rate. Once you go into higher speeds (although the later batches get it even at original speeds from what I see)you start hitting HW error rates. If there is more than 0.01%, IMO your miner is more irrational than stable and could impact the miner hardware or the income generated from it towards the pool.
On new gen hardware there should be pretty much no HW errors and comparing it to an old miner tech that is 3 generations or more previous is like saying that your 1990 Nissan Sentra sounded like a lawnmower and it is ok for a brand new 2015 model to have the same shitty sound.