Intel-undervolt: CPU undervolting and throttling configuration tool for Linux

Why would I want this? With a properly configured kernel, Intel chips can downclock to somewhere in the 400-800mhz range when idle.

iirc a lot of Intel chips (12th gen+ esp) can be slightly undervolted to achieve better power efficiency and lower temperatures with negligible impact to clock speeds. particularly useful on laptops, mini PCs, and desktops that spend a lot of time at idle.

Undervolting can make your CPU use less power and produce less heat. It’s popular for people attempting to overclock because of the thermal headroom it gives- essentially its the same concept as overclocking in that the silicon lottery can mean CPUs can be better than their factory tuning because Intel is hitting the lowest common denominator in the stock config.

I have used this to moderate success on a 8th generation mobile Xeon to drop the temps ~7C under load, and get the system idle from 6w to 4w (going lower would have been really hard as at that point the CPU was responsible for very little of what remained).

Undervolting is not the same as downclocking, it is supplying less voltage which has a strangely profound impact with no performance loss. However your system can be much less stable.

Where can I find out more about this? Just picked up an i5 13500 and my primary concern is low power usage.

Basically the same as overclocking; set, test, reset, retest ….

Be careful with the verification runs as they can easily eat up the energy savings that you are trying to archive

> a strangely profound impact

Something like power consumption being proportional to the square of voltage iirc.

Check here:

https://www.reddit.com/r/buildapc/comments/14kll95/intel_i5_...

it seams -100mv - -150mv is the maximum (maybe not stable) undervolting.

In the interest of simplified manufacturing and support, they leave some power consumption on the table.

You can take that back and get a little more juice, at the risk of instability or time.

No automated system is perfect, /shrug

Because the CPU is never idle, there’s always some JS jockey’s piece-of-shit Electron app redrawing in a hot loop, some manic search tool re-indexing all the contents of all mounted drives etc

Mobile Xeon? Pardon?

Undervolting mostly helps with power consumption under load.

To add to this, undervolting isn't about idle clocks, but temperature and power control under load. I typically only apply them to "turbo" boost clocks, which are a frequent cause of thermal throttling even with water cooling.

Intel's 13/14th gen CPUs draw significantly (~70-100W) more power on boost, which can stress the VRMs in otherwise correct pairings and lead to current/EDP or power limit throttling. Lowering the voltage at certain frequencies can allow the system to sustain higher clocks without performance degradation.

Yeah, Dell Precision 5520 with Xeon E3-1505Mv6

I loved it.

https://www.dell.com/support/manuals/sv-se/precision-15-5520...

There are multiple tiers of Xeon. The “base” tier (I am very much over-simplifying) is the same silicon as consumer desktop/mobile with some features turned on like ECC. Mobile workstations and the like get Mobile Xeons. It’s less crazy than Desktop Replacements with socketed Desktop CPUs.

You can underclock most laptop CPUs by 50-100mV without losing any performance. They’re usually tuned so far into diminishing returns out of the factory that it’s free efficiency.

Undervolting is not underclocking. With undervolting, you keep performance the same, but use less voltage. It requires trial and error to find the "magic value" that you can reach without experiencing system instability.

Why would you not want this, a properly undervolted system loses no perf and gains lifespan and draws less power. Amortized over the now increased lifespan of the processor you could end up with hundreds of dollars of savings, especially in a laptop where a dead CPU or battery often results in a full system replacement. Undervolting is why my 4 year old HP laptop still gets 6 hours of battery life even with heavy mobile use every day.

It’s a pretty fuzzy barrier anyway. Like the original Skylake i9 desktop chips were basically just Xeons, right? It isn’t like there’s anything magic in a Xeon, it’s just a bunch of cores, why not pop one in a laptop… just don’t hurt your back carrying the power brick.

Still rocking my Intel Xeon E3-1545M v5 (Skylake) from 2016. It was the only way to get ECC ram on a mobile workstation.