I just installed an NH-D15S yesterday on an Intel 8700, and am seeing a 30 degree Celsius drop in my temps under load.
I don't overclock (obviously) but under load with the stock cooler I was running in the mid-90s Celsius, and occasionally it seemed to hit the thermal limit and back itself off.
I installed the NH-D15S, and with Prime95 and other stress tests, I never went over 63C. I was very impressed with the ease of installation, although this would be even easier if I took the motherboard out of the case. It is super quiet, perhaps not silent on full load, but very nearly silent. I also like the greater compatibility of the D15S: The offset heatsink gives you mounting options, and one fan was plenty to meet my needs.
My setup, for compatibility info:
i7-8700
Corsair Vengeance RAM
Asus TUF Z370 Gaming Plus motherboard
Corsair Carbide 200R case
I would check out the measurements carefully to ensure it will fit in your case, it comes pretty close to the side panel on my 200R. Great performing cooler