Quote Originally Posted by Boxen View Post
I don't intend to overclock the 3900X at all. Stock performance will be more than sufficient. This upgrade was all about cores, not MHz.
That's exactly why I chose to go with the 4.2GHz all-core OC and 1.25v undervolt. What I was seeing in initial testing was relatively poor cinebench R20 scores, likely as a result of a really high 4-6 core 4.5GHz auto-boost at something like 1.475v, followed by a rapid temperature spike, followed by thermal throttling. I played with voltage a bit on mine and really wasn't able to go past about 4.2GHz with any consistency at any voltage, so I just left it at 4.2/1.25V. The scores are up where they should be, the system runs cool, and I don't have any more bizarre "surges" in individual cores as it tries (and struggles) to allocate boost clocks. I went through about a solid week of futzing with configs to find what kept things down below 70C under stress loads while still yielding good benchmarks in the tools I use regularly (games, 7-zip, ffmpeg) and it's been superb since I just left it where it's at. It feels like having two PCs worth of power in one versus my i7-6700K.

The one thing I did do a little different this build was pick up a license for http://www.argusmonitor.com/ and use it to micro-manage fans/pumps rather than trusting the janky NZXT fan software or the somewhat limited BIOS fan controls. I was able to tune down the EVGA water pump (with a fan-header conversion cable) so the pump whine is now gone. I also set the chipset fan to start spinning at 40C and slowly ramp up, which keeps chipset temps down around 45C at idle and ~60C max, versus the stock setting which had it sitting at 65C+ at idle and 75-80C under load. I'm sure it would have been fine as I'm not really stressing the board in my use cases, but I prefer my equipment to run as cool as possible which greatly extends component life.

Anywho, happy hunting!