Modern Intel CPU's with dedicated graphics, include a core that is dedicated to H\W coding and decoding. From 9th Gen onwards these cores really pack some punch.
Is QuickSync required : No, infact CPU decoding is slightly more accurate and more compatible.
Will QuickSync Help : Absolutely, you need to decode footage for BI to process motion triggers.
When to use Quicksync : You want the most efficient setup possible. Decoding via Quicksync is more efficient than CPU and a lot more efficient than GPU (GPU is faster but not very efficient)
Older computer. using quicksync frees up the CPU cores, so it's like free computing, or wasted computing if you don't use the quicksync core.
Modern CPU, sure the CPU's are super powerful with tons of cores, however they also come with one hell of a powerful decoding\encoding core. What a waste if you don't use it.
It's wrong just to look at CPU utilisation alone, CPU's adjust their core speed as required, so you need to check utilisation along with clock speed. Remember a CPU at 80% utilisation running at base clock speed is consuming less power than a CPU with 10% utilisation running maximum clock speed. ie: getting work off your CPU may allow the compute cores to drop down clock speed reducing heat and power consumption.
For viewing (H.264 only) you should also try "direct-to-wire", that basically uses no measurable CPU to view live footage.
QuickSync, Direct to Disk, Sub-Streams, Direct-To-Wire, you can basically run
BlueIris from the smell of an oily rag.
