Pi itself is not rebooting or restarting right ? Only the monitor was going on/off. If pi is going on/off , then that will be bad, it can easily dry the sd card,
I think the fan is doing something, check if changing the relay has any effect (i.e. try another channel that you know works alright, like the one thats controlling light right now). If you can isolate the problem, it will be easier to fix.
Going to do a bit more testing to find the exact problem... It might be as simple as i do not have the relay grounded to the power source YET
My thinking is its the cheap relay.. I bought a cheap one for testing.. My Production version i will use High end single relays .
