So, title basically says it all. It said on the package that "Activates when needed" and it is supposed to spin when CPU usage is over 20%. However, even when playing Battlefield 3, CPU usage is well over 30% and even when stressed by Prime95, it stays dead. Only time I have ever seen it spin, is during start-up. So, is there a way to "over-ride" this system and keep it running permanently?
I would guess, without knowing your systems specs, that you are barely working that 800w power supply. But to answer your question, no there is no way to override it. It will spin up when it senses that the psu is getting warmed up.
both techpowerup and hardware secrets say that PSU's (or platform) fan remains off at low levels but don't state when the fan does begin to spin (its doubtful it spins at 20% CPU usage but rather when the PSU hits a certain temp)
FYI, hardware secrets called the 700w version "flawless" while techpowerup gave a very good review to the 800w version