Vorta, did you do any fan mods?@
Yes, I have (ended up doing
this). 2x Scythe Ultra Kaze (push-pull) has proven to be the best in airflow vs. sound ratio. You'll also be able to overclock your miner.
Push-pull combination will always work better than any push-only configuration on the S5 because of a lot of air escaping the heatsink before reaching it's end. I would recommend not buying Deltas as they are very loud. I would also not recommend overclocking the miner while using only one fan. Unless you have an infrared thermometer to monitor the temperatures of chips in the back of the miner ensuring they don't go over 90°C as you're testing the frequencies.