"The fanless results shown above were much better than I expected. I had personally expected it to cool closer to 100W over long terms, 150W was beyond my wildest expectations! This basically means that for common tasks – web browsing, gaming, etc. – you won’t notice any performance difference (vs normal coolers) using Noctua’s fanless NH-P1.
But there are other ways to look at this cooler’s performance. I wanted to see how long the NH-P1 could sustain workloads without having the CPU hit TJmax. With a 200W TDP enforced, it lasted 2.5 minutes (picture below shows after it hit TJmax)"
Source: Boring Text Reviews
