Fan upgrade on B3 went well. I had already applied both firmware updates to my B3 to increase hashrate and to show fan speeds. It was running a bit warmer after updates and was 40-50C chip temps with fans going 4800-4920 rpm. Disconnecting exhaust fan did not have noticeable effect on temps but was running quieter. Changing fans to
https://www.corsair.com/uk/en/LED-Co.../CO-9050039-WW ( I bought mine on Amazon a bit cheaper) has increased temps to 50-60C chip temps with ambient temp around 25C. Running only one of these fans does not make much difference to noise but temps go over 60C so best to run both. They are running at about 2000-2160rpm and are a lot quieter, it's hard to measure noise due to ambient noise and it seems PSU is now running louder than B3. I estimate it being about 60dB now so almost 4 times quieter than 75-80dB it was before. Fans are rated 37dB but it makes extra noise as air travels through the miner.The key for fan plugs is different so I had do cut off bits from fan plugs to make them fit. I also used shorter screws to make sure they do not touch anything inside.
Little rise in temps has not had any affect on hashrate and it's still hashing over 1000 H/s and warranty stickers are still intact as those are only on body screws not on fan screws.