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DPete27
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Share Your GPU Undervolt

Thu Feb 16, 2017 12:24 am

There's been some discussion in various threads about undervolting GPUs to cut down on power/heat/noise, so I figured I'd share my findings here and make a place where others can share their results about cutting power consumption without giving up performance

This is a rudimentary guide from my experience undervolting my RX480
First off, there are many power saving options offered in the AMD settings.  "Power Efficiency", Frame Rate Target Control", and "Chill".  As far as I know, unless you enable at least one of these settings, or an in-game framerate target setting, your GPU will simply run at it's max frequency (State 7) at all times in games.
Power Efficiency:  Not 100% sure what this setting does, but I was able to use it effectively in Rise of Tomb Raider to lower power draw by an average of 15W without affecting framerates.  I used that feature while Global Wattman was set to Auto voltage.
Frame Rate Target Control:   This feature allows the GPU to dynamically downclock itself to only deliver a max of the target frame rate.  I have this enabled in global settings to cap framerates at my monitor's 60Hz native refresh rate.  No use in running your RX480 at max clocks to play LoL at 1000fps if your monitor is only showing you 60fps.  This has obvious power saving benefits depending on how un-demanding the game is.  It also effectively serves as a (IMO) more desirable (albeit not quite as consistent) form of VSync because it doesn't introduce added latency.  The downside of FRTC, is that it only works on DX9/DX10/DX11 games so far.
Chill:  Works similar to FRTC, with some added features.  Easier to just point you at TR's article on Chill.  I haven't dabbled with this much, since it seems to apply more to FreeSync monitors.  Worth noting that AMD's Whitelist of games that support Chill is pretty scarce at the moment.

Now, to the undervolting.  To do this in AMD Wattman, you'll go to Global Settings -> Global Wattman and toggle the GPU voltage control from Auto to Manual.  This will populate the GPU core voltages from State 1 to State 7 (these are load states), as well as the memory frequency State 1.  I also have frequency set to dynamic which shows the clock speed at each state.

First you'll want to test for the lowest memory voltage your card can run stable (I used FurMark and Doom-Vulkan to test my settings).  I've found that the memory voltage seems to act as the lower limit of core voltage (ie, if my memory voltage was set to 975mV, the core would receive a minimum of 975mV also, despite core voltage settings being less than 975mV for the frequency being tested).  My RX480's minimum stable memory voltage was 900mV.  My card idles at 300MHz/800mV.

Once you get a stable memory voltage, start by lowering your State 7 core voltage.  Depending on what your particular GPU's advertised boost clocks are, and ASIC quality, will determine what the core voltage can be.  My 1305MHz state is plenty stable at 1030mV for example.  Test your settings for State 7.

Next, set the State 7 frequency and voltage equal to the values in State 6.  When you benchmark (with power saving features off), the GPU will ramp up to State 7.  In order to test the lower States, you'll need to set every State higher than the one you're testing to be equal (ie. if you're testing State 5, frequency and voltage of States 5,6,and 7 need to be the same).  Proceed down the states as far as you like.  I tested States 5-7.

I found that creating an Excel scatter plot of my Frequency/Voltage curve helped visualize what intermediate states should be if you don't want to test for voltage at every state. If you set the Voltage Control toggle back to Auto at any point, there's a good chance your voltage curve will be lost, so it's nice to have a record of what you found stable.

One last thing.  Since I tested in Doom - Vulkan, I found that power saving features like Power Efficiency and FRTC didn't work and my GPU ran in State 7 at all times.  Even 1235MHz on my RX480 @ 1080p and Ultra settings produced 120+fps, which is wasteful on my 60Hz fixed refresh rate monitor.  You can enable game-specific frequency curves by clicking on the game in AMD settings and navigating to Profile Wattman.  

TL;DR, here are the settings I tested stable on my MSI RX480 Gaming X 8G:
Some people like to also reduce maximum frequency to avoid the range of exponential voltage increases needed to maintain higher frequencies than a GPU/architecture is comfortable with (AMD Hawaii GPUs were notorious for being pushed beyond their comfortable range by AMD).  My personal opinion is that I paid for the clock frequency of my card, so I'm not going to give that away.  Hence I'm only doing voltage adjustments and leaving my card's frequency curve alone.
ASIC Quality = 80.1%
Memory Voltage = 900mV at 2000MHz (8GHz effective)
Core Frequency/Voltage = 610MHz/818mV - 910/840 - 1075/880 - 1145/900 - 1190/910 - 1235/925 - 1305/1030.
Power usage as reported by GPU-z: Doom - Vulkan = 135W@1305MHz, 110W@1235MHz. Furmark = ~100W@1305MHz, and ~80W@1235MHz. Auto voltage setting wanted 1150mV for 1305MHz = 130W in Furmark.
[Updated after more testing in the 1190MHz-1235MHz range.]

Share your results!!
Last edited by DPete27 on Mon Mar 27, 2017 10:09 am, edited 3 times in total.
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Re: Share Your GPU Undervolt

Thu Feb 16, 2017 8:16 am

I managed to downclock and downvolt on GTX 1070 to 1708MHz core / 0.825V / 80% power limit from stock GPU boost ~1900MHz core / 1.05V in MSI Afterburner on custom voltage curve. Essentially I'm getting 90% of max stock performance but at 1/2 the TDP, but at the cost of RAM running at full speed wasting power for video decoding for some odd reason which is still something I couldn't manage to solve. It's rather insane how much NV overtuned GP104 and the same reason why I dislike auto overclocking features.
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ptsant
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Re: Share Your GPU Undervolt

Thu Feb 16, 2017 8:38 am

I can confirm that my RX480 runs stable on 1240/975mV but anything below depends on the game. I run the memory at default settings, I don't think it matters much for power consumption and I did get some weird crashes when I tried 950mV.

I had measured the difference in maximum total system consumption to something like 50W (see on of my posts on the subject here: viewtopic.php?f=3&t=118160&p=1325144&hilit=ptsant#p1325866 )

As I reported earlier, anyone with an RX480 should at least try 1240/1000mV for core. If you want more perf, 1300+/1075mV may or may not work.
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DPete27
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Re: Share Your GPU Undervolt

Thu Feb 16, 2017 9:49 am

ptsant wrote:
I run the memory at default settings, I don't think it matters

DPete27 wrote:
 I've found that the memory voltage seems to act as the lower limit of core voltage

My RX480 ran itself at 1305MHz/1075mV on auto at times, so I'd imagine that's a relatively safe bet for manual tweaking.  Other times it would go up to 1125mV.  Good point about measuring "stock" power draw though.  Testing ran late into the night last night, so I did my best to scramble together a forum post before I went to bed.  I'll have to update my original post with that info.  If I get time, I also want to drill into my voltage setting at 1235MHz.  I suspect my voltage setting of 975mV is still a bit conservative for that frequency, but it fit the curve well.
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ptsant
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Re: Share Your GPU Undervolt

Thu Feb 16, 2017 10:02 am

DPete27 wrote:
ptsant wrote:
I run the memory at default settings, I don't think it matters

DPete27 wrote:
 I've found that the memory voltage seems to act as the lower limit of core voltage

My RX480 ran itself at 1305MHz/1075mV on auto at times, so I'd imagine that's a relatively safe bet for manual tweaking.  Other times it would go up to 1125mV.  Good point about measuring "stock" power draw though.  Testing ran late into the night last night, so I did my best to scramble together a forum post before I went to bed.  I'll have to update my original post with that info.  If I get time, I also want to drill into my voltage setting at 1235MHz.  I suspect my voltage setting of 975mV is still a bit conservative for that frequency, but it fit the curve well.

I was unlucky in the chip lottery and got a relatively bad chip quality but I do have a very nice PSU. For an average chip I think 950mV should be doable at 1240MHz. Going below 950mV is probably only possible with the best chips and may not even be completely stable in all workloads.
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Re: Share Your GPU Undervolt

Fri Feb 17, 2017 1:57 am

Not RX 480 but running HD 7970 - 1050 MHZ @ 1030mV currently.
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ptsant
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Re: Share Your GPU Undervolt

Fri Feb 17, 2017 2:30 am

Jigar wrote:
Not RX 480 but running HD 7970 - 1050 MHZ @ 1030mV currently.


That is quite an aggressive undervolt. I ran mine at 1090mV/1000MHz but undervolted at the BIOS. I could go a bit lower but didn't want to risk putting it into the BIOS.
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Re: Share Your GPU Undervolt

Fri Feb 17, 2017 4:02 am

ptsant wrote:
Jigar wrote:
Not RX 480 but running HD 7970 - 1050 MHZ @ 1030mV currently.


That is quite an aggressive undervolt. I ran mine at 1090mV/1000MHz but undervolted at the BIOS. I could go a bit lower but didn't want to risk putting it into the BIOS.


Actually these numbers are set in bios, since recently after 4 years of service my card refuse to run at 1100 MHZ @ 1175mV. Also, i am not playing any demanding games these days and usually playing Dota 2, DOOM or WarHammer 40K which works perfectly fine at full HD resolution. I think i wont mind if my card last me 2 more years as that will make this card my longest serving graphic card (6 years).
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ptsant
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Re: Share Your GPU Undervolt

Fri Feb 17, 2017 6:32 am

Jigar wrote:
ptsant wrote:
Jigar wrote:
Not RX 480 but running HD 7970 - 1050 MHZ @ 1030mV currently.


That is quite an aggressive undervolt. I ran mine at 1090mV/1000MHz but undervolted at the BIOS. I could go a bit lower but didn't want to risk putting it into the BIOS.


Actually these numbers are set in bios, since recently after 4 years of service my card refuse to run at 1100 MHZ @ 1175mV. Also, i am not playing any demanding games these days and usually playing Dota 2, DOOM or WarHammer 40K which works perfectly fine at full HD resolution. I think i wont mind if my card last me 2 more years as that will make this card my longest serving graphic card (6 years).


Mine also served for a very, very long time and I would probably have kept it if I didn't want FreeSync. It still works in a secondary PC, in fact.
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Re: Share Your GPU Undervolt

Fri Feb 17, 2017 8:20 am

Need to double-check when I get home but I think I'm running a Gigabyte RX480 8GB reference board at 1275MHz/925mv and I'm limited in my undervolting by the Memory not the GPU.

Sure, you can set your GPU to 900mv but if your GDDR5 is set to 1000mv then all the tools report the GPU voltage as 1000mv.
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Re: Share Your GPU Undervolt

Wed May 10, 2017 5:46 pm

Just an update to this thread, the old RX480 wasn't quite stable in the long term at 925mv - I think it was actually the VRAM that needed more juice in a couple of games so when I came to test this RX580 I noted that I'd been running 1275MHz @950mv all this time.

This RX580 (Sapphire Nitro+) seems to be very similar. I've stuck it on 1300MHz @1000mv for now and will perhaps update this post if I feel inclined to search for the optimal speed at the VRAM's lowest stable voltage.
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Re: Share Your GPU Undervolt

Fri May 12, 2017 6:53 am

I have an Asus Dual RX 480 O4G (4GB) overclocked with afterburner to 1340Mhz core /1850Mhz memory. I get stable 1340 core in Withcer 3. No crashes at all. Max temp is 83c with fan speed max 76% (custom curve). Default voltage. Powelimit +20.

I have a big room with large windows and room temp goes upto 50c and lowers slowly to 28c after I turn on aircon. In winters max GOU temp was 75c.

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DPete27
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Re: Share Your GPU Undervolt

Fri May 12, 2017 9:24 am

Maning. I assume you're on auto voltage then? What does the core voltage read in GPU-z when the GPU is loaded?
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Re: Share Your GPU Undervolt

Sat May 13, 2017 9:12 am

DPete27 wrote:
Maning. I assume you're on auto voltage then? What does the core voltage read in GPU-z when the GPU is loaded?

It goes upto 1.313V at full load.
 
DPete27
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Re: Share Your GPU Undervolt

Mon May 22, 2017 8:59 am

manig wrote:
It goes upto 1.313V at [1340MHz].

You'd probably be able to run 1340MHz @ 1.100 mV if you manually set voltages. Probably start and see if you can do 1340MHz @ 1.150V first and back down from there. See my first post in this thread for guidelines. Setting a manual voltage curve will likely save you a BUNCH of watts/heat. Probably close to 50W.
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Re: Share Your GPU Undervolt

Mon May 22, 2017 12:48 pm

DPete27 wrote:
manig wrote:
It goes upto 1.313V at [1340MHz].

You'd probably be able to run 1340MHz @ 1.100 mV if you manually set voltages. Probably start and see if you can do 1340MHz @ 1.150V first and back down from there. See my first post in this thread for guidelines. Setting a manual voltage curve will likely save you a BUNCH of watts/heat. Probably close to 50W.

Sorry its not 1.313v but 1.131v at 1340/1850.

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