BTW just to check - is it just your screen turning off (shouldn't really affect the render tbh), or is the computer actually going into some sleep/hibernate mode too, or hard drives powering down? My screens do turn off after 45 mins, but nothing else ever powers down, and it has no effect on rendering (in fact, two of my nodes have no screens anyway). If it is just screen powering down and everything else remains powered up, are you using NVIDIA as a denoiser, or the regular Corona denoiser?
Cheers!