I know that as FFT size is increased, spectral (frequency) resolution increases and temporal resolution decreases (and vice versa when FFT size is decreased).

According to: (Frequency Resolution) = (Sampling rate) / (# FFTs)

However, I am uncertain about how this relationship affects the the PSD (power spectral density). Does the accuracy of a PSD change with FFT size, and if so, does it do so in the same manner?