Completely silent when paired CPUs with up to 120 watts TDP. If go any higher you WILL hear the fans. The highest core count CPU which allows silent operation with this Heatsink is E5-2695v4, so in a dual cpu configuration this will give you 36 cores (72 threads).
This was used to replace a failed high-performance liquid cooler in a Z820, and so far, it's been working great! No more liquid, no more failed gaskets, hopefully no more headaches.