Ryzen 9 7900X Owner Details How To Cut Power Draw In Half With Minimal Performance Loss

ryzen 9 7900x in socket
If you keep up with hardware news and reviews like ours, then you're no doubt already aware that AMD's Ryzen 7000-series processors run hot by design, and they can be pretty power-thirsty, too. In ages past, we'd fix a problem like this through undervolting, and that's exactly what Reddit user MyKillK has done with his Ryzen 9 7900X.

We saw rumblings of this kind of thing in rumors well before the CPUs actually hit the market. This result isn't quite as great as that result, because while MyKillK did manage to halve his power consumption, he sacrificed a smidgen of performance to get there. Specifically, the numbers he offers up pull from Cinebench where a 1% drop in single-threaded performance and an 8% loss in multi-threaded are the consequences of his tweaking.

reddit zen 4 undervolting
MyKillK's explanation of his BIOS settings.

The benefits? He dropped his CPU package power draw down to just 97 watts—a drop of around half from the stock value. This had effects on his temperatures too, as you can imagine. While Zen 4 CPUs are designed to ride the ragged edge of their thermal limit at 95°C, MyKillK's 7900X is staying at a relatively-cool 75°C under "the most extreme testing," which sounds like OCCT AVX Linpack based on his other comments.

These benefits were achieved through a careful process of tweaking and testing over the course of several hours. MyKillK combined a general core voltage offset with Ryzen Master's Curve Optimizer function to end up with a -50mV overall undervolt and then individual offsets for each core ranging from -30 to -27 mV. This results in per-core undervolts between 77 and 80 mV, lowering the core voltage from ~1.4V to ~1.31V.

oc 1 ryzen 7000 performance
AMD didn't push these chips all the way to the edge, contrary to early reports.

The Redditor admits that he's not completely sure the system is totally stable, but that it hasn't given him any trouble despite constant usage and brief stress testing over the last day and change since his original post. Most likely, the thing most affecting his performance is the -100 MHz PBO boost override setting. It certainly helps with stability but will drop performance slightly.

We haven't tested undervolting with the Ryzen 7000 series yet, but it looks like AMD's gone for pretty high safety margins. It's possible that AMD was concerned about competing with Intel's forthcoming Raptor Lake CPUs, and that's why it elected to push the chips so far past their frequency/voltage sweet spot. Whatever the actual reason, it's clear that Zen 4 users interested in tweaking can drastically reduce the power consumption of their new CPUs without shaving too much performance off the top.