Undervolting Guide

[SomeGuyonTHW]

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Why undervolt?
Most graphics cards consume more power than they need to, this is because of stability, not all chips are equal, some can work fine with a certain voltage that is lower than factory, some can't. all GPUs sold must be fully stable in all workloads out of the box, hence a higher voltage than what is usually needed is set for everyone, as companies won't go through optimizing each and every card for best efficiency.

Can undervolting damage my GPU?
No, you're safe, worst case scnario is your games crash because GPU isn't being fed with enough power.

You can have three end goals by undervolting:
1. Running GPU with a higher frequency than stock at lower voltage compared to stock. (Aka Overclock + Undervolt)
(A tiny bit more performance, at a bit less power compared to default settings)

2. Running GPU with the same frequency as stock, at a lower voltage.
(Same performance as default settings, at a lower power)

3. Running GPU with the same frequency as factory has specified, at a significantly lower voltage, this is without the automatic boost (e.g 3080 FE which runs at 1950 MHz instead of the 1710MHz specified by Nvidia as boost clock)
(A bit less performance compared to stock with significantly less power)

To make something clear, in my own testing I came to the conclusion that your frame rate in games does not scale linearly with frequency, e.g., adding 5% to frequencies does not mean 5% more FPS (and vice versa) if we're talking about 1900mhz and 1990mhz on 3080 chances are frame rate difference in some games is less than 1 FPS, or 5 at best.
We're aiming for max efficiency here; so main focus is on the third one as it is (in my opinion) almost always the best option (especially for recent GPUs)
By the end of this How To you should be able to do 1. and 2. on your own.

Tools:

1. Heaven Benchmark or a GPU intensive game or task, if you have one [1]
2. MSI Afterburner
3. GPU-Z

Guide with Explanation
Step 1:
Open GPU-Z, in the Graphics Card information panel, look for Default Clock in front of it is Boost.
As an example, for a 3080 FE this value is 1710MHz, this is the lowest possible frequency all 3080s are guaranteed to run at or let's call it Factory boost clock spec (your GPU boosts as high as it can which almost always exceeds this number)

Step 2:
Click Sensor panel in GPU-Z, click the 3 lines button on the top right corner to open GPU-Z settings, click sensors tab, set "Sensor display mode" to Highest.
Open Heaven Benchmark and let it run for a minute.
Observe the highest GPU Clock, this is as high as your GPU boosts at stock settings.

Step 3:
Open MSI Afterburner, decrease Core Clock by:
[Maximum Stock GPU Clock] - [Factory Boost Clock Spec]
e.g: 3080 Founders edition has a boost clock specification of 1710MHz, while all 3080 FE cards run at around 1965 MHz
You will underclock by 255MHz (1965-1710), if you have a 3080 (any 3080) it doesn't matter if you underclock by this exact same number, but if you have another card, it is better you do the first 2 steps.

Before continuing, how does the Voltage/Frequency Curve behave?
Basically, you are telling the GPU to run at X voltage for a frequency.
If frequency increases as voltage does, GPU will consume more power and try all it can to achieve your desired frequency at the voltage you have specified.
But if frequency stays the same as voltage increases, GPU will use the lowest voltage value on the curve to run at your desired frequency, it won't try to increase voltage, you're basically giving it a frequency/voltage cap. (Aka a flat curve)

Step 4:
From now on you will have Heaven Benchmark always running after each attempt at undervolting.
For any meaningful undervolt, you will want to run at 0.900mV or less. 0.9mV is usually a safe voltage high enough to allow you to run at Maximum Stock GPU Clock, but we can go lower for lower power consumption and almost identical performance.
- Open Curve Editor in MSI Afterburner, you see a bunch of squares connected to each other, each one defines a frequency at a certain voltage.
A good start is just below 0.9mV, select the square and drag it up to your desired frequency, hit apply in MSI Afterburner and the curve should automatically flatten. for example, you've chosen to run your 3080 with 0.850mV@1800MHz, then do a stability test with Heaven Benchmark. Keep in mind setting a frequency that is too high for the voltage can result in crashing, have realistic expectations.
For most GPUs you can run factory boost clock spec at under 0.775mV (this is only a starting point, if Heaven Benchmark crashed with 0.775mV with Factory Boost Clock Spec) you can try increasing the voltage.
if it didn't crash, you can try lowering your voltage by one square/point on the curve, until it is unstable again. then increase it by two (1 extra for insurance in some scnarios)
If you found your desired voltage/frequency, test some of your applications, there's a good chance they will crash if Heaven Benchmark didn't, and you will have to increase the voltage again by one or two points, until it is stable.
(Note: You have to reset the curve by hitting reset button and underclock again like in step 3 after each attempt)

[1]: Heaven Benchmark is not the best tool to test stability but as it launches quickly and since you will crash a lot until you're done, something that opens up quickly is something you'd want.

Notes:
Running at factory boost clock spec has a great advantage, while you might have a harder time to find fully stable settings and maybe have a little less performance, it is very rewarding.
You can run almost any GPU at 60% of its max TDP, which is insane, I have done this to several Nvidia 30/20/10 series cards in the past, flawless.
For instance, you can definitely run a 300w 3070ti at just around 200w (which is a ~50% decrease, at cost of a few frames)


For a long time, I had a difficult time understanding what undervolting guides on YouTube are saying or was worried if I'm doing something wrong because even the voltage/frequency curve looked like a mystery to me as no one really explained how it works.
After watching many tutorials, I came to my own conclusion and understanding and I thought it would be a good idea to share, hopefully this helps someone. 👍

 

[cdrkf]

Nice guide - I think your scenario 1 depends on the GPU in question. There are a few notable gpu's where the vendor set the voltage so high it actually hurts performance due to increased thermals.

A good example of this is AMD Vega 56 and Vega 64 cards - they typically run faster with an under-volt without changing any other settings thanks to the reduction in thermal output.

Also regards running cards with most of the performance at a big reduction in power - this is down to the fact that nVidia and AMD are both pushing their cards to the absolute limit these days (RTX 4090 for example) - they are running them well above the optimal point in the voltage frequency curve. When you lower the voltage and frequency targets a bit you move back towards that optimum so the drop in performance is negligible.