The FutureBit PSU is already derated to 80%, its designed to run @ 200 watts 24/7. If this was a normal ATX PSU it would be marketed as a "250W" PSU.
Does the stock PSU offer any leeway to OC the hashboard? Mine is practically at 2 weeks uptime, seems to be very stable SW, looking forward to the bitcoin apps you're working on.
Is the miner's hashrate supposed to match the slushpool's hashrate on the Apollo Dashboard?
Apollo Dashboard -
https://ibb.co/940wnHkApollo Detail -
https://ibb.co/3F6vj3MSlushpool Detail -
https://ibb.co/q9FvSZRIf you follow the 80% "rule" there's no leeway. There are some discussions above regarding more powerful PSUs but keep in mind potential thermal issues.
The miner and the pool rates will never exactly match. The miner hashrate changes constantly as does latency between miner and pool, the rate of the pool's UI updates, and so forth.