The silent mode will drop the fans and use passive cooling, however it will likely also use processor throttling to maintain passive heat levels.

it means you can use the system harder for longer but it needs the fan, or less hard or harder but for shorter periods of time with them off

The silent mode will drop the fans and use passive cooling, however it will likely also use processor throttling to maintain passive heat levels.

It means that with passive cooling the system will only be able to use the processor at 100% for a short period of time before it will have to reduce the speed of the processor (and also the power going to it) to reduce heat generation until the system has cooled down.

in active cooling (the fans on) the system can dissipate the heat easier

therefore in passive cooling you can only use the processor at a high load for a short period of time.