Nvidia 4090 Power limiting & undervolting in VR

[NBee]

Just want to share my experience with power limiting and undervolting my Geforce 4090RTX in DCS 2.8.2.35759 Open Beta

Settings in:

OpenXR Tools for WMR is custom render scale ON and 100% MR Disabled

OpenXR ToolKit: Turbomode ON

 

The data below is recorded with OpenXR ToolKit by replaying the same track file in VR (HP reverbG2)

Ignore the first 8-10 sec of the graph since this is a recording of starting the track file and activating with OpenXR ToolKit.

 

[edmuss]

100W less for 3fps reduction isn't bad!
I've not actually looked at the power reduction from undervolting my 3080ti, not sure it's that high, pretty sure I'm still pulling 320w out of it but that's not at stock clocks.
What were the clocks like for the OC bios?

[speed-of-heat]

this is essentially what i am running (the orange profile)

[freehand]

When I first under volted my 3080 in DCS some of the building looked white and lost some colour, not sure if it was just a DCS thing and was a while ago, so be careful you're not flying over igloos instead of normal building.

[NBee]

30 minutes ago, edmuss said:

100W less for 3fps reduction isn't bad!
I've not actually looked at the power reduction from undervolting my 3080ti, not sure it's that high, pretty sure I'm still pulling 320w out of it but that's not at stock clocks.
What were the clocks like for the OC bios?

In DCS the GPU speed is relatively stable around 2715 MHz in the OC Bios.

[NBee]

13 minutes ago, freehand said:

When I first under volted my 3080 in DCS some of the building looked white and lost some colour, not sure if it was just a DCS thing and was a while ago, so be careful you're not flying over igloos instead of normal building.

I have not experienced that there is a difference in the graphic quality of DCS when I test. However, it is absolutely certain that DCS crashes if I experiment with adjusting the Memory clock in MSI afterburner.

[Steel Jaw]

I played with this and found zero beneficial effects, so no sale, but thanks.

[EightyDuce]

Any reason to lower power limit on top of a power curve, seems redundant? 

Reason I ask, and I'll have to verify when I get home to make sure I'm not talking out of my 3rd point of contact, if I recall I had better performance with power curve only VS OC, or power limit. 

Current power curve is 950mv +200mhz (~2745mhz core) +1000 on Vram. Same or better performance at almost 100w less stays boosted to 2745 almost indefinitely, load Temps about 47C on a custom loop. 

Could you share the track file to try? 

[NBee]

20 hours ago, EightyDuce said:

Any reason to lower power limit on top of a power curve, seems redundant? 

Reason I ask, and I'll have to verify when I get home to make sure I'm not talking out of my 3rd point of contact, if I recall I had better performance with power curve only VS OC, or power limit. 

Current power curve is 950mv +200mhz (~2745mhz core) +1000 on Vram. Same or better performance at almost 100w less stays boosted to 2745 almost indefinitely, load Temps about 47C on a custom loop. 

Could you share the track file to try? 

You might be right in your assumption I’m not a specialist.

 

But I’m thinking like this:

 

I want to save power (My PSU is only rate to 750W) and at the time get a stable clock speed that gives me a minimum FPS count > 45 with a low FPS fluctuation.

 

So, my approach is the following:

 

Power limit Is the max power the graphic card is allowed to use. And within this limit the card will try to reach max clock speed, and when it then hits the power limit it will throttle down meaning that there is a risk of getting unstable/fluctuating clock speeds as a result.

So, if you at the same tells the card to never to exceed 2700MHz above 950mV then you “hardcode” the highest possible stable clock sped available within your set power limit and thereby in “theory” this should  minimize the fluctuation of FPS.

I have attached the track file that I used Mirage2000 vs SU 33 over Syria.

2 mirage vs su33.trk

[jnr4817]

22 hours ago, EightyDuce said:

Any reason to lower power limit on top of a power curve, seems redundant? 

Reason I ask, and I'll have to verify when I get home to make sure I'm not talking out of my 3rd point of contact, if I recall I had better performance with power curve only VS OC, or power limit. 

Current power curve is 950mv +200mhz (~2745mhz core) +1000 on Vram. Same or better performance at almost 100w less stays boosted to 2745 almost indefinitely, load Temps about 47C on a custom loop. 

Could you share the track file to try? 

How are you finding this +200/1000mhz for the 950 limit? What are you doing to test. I just got an Msi 4090 suprim liquid. Currently all I’ve done is turn the power limit up to 110. However undervolting seems like a good idea and I’d like to extend the service of my gpu. They are like investments now. 

[EightyDuce]

1 hour ago, NBee said:

You might be right in your assumption I’m not a specialist.

 

 

 

But I’m thinking like this:

 

 

 

I want to save power (My PSU is only rate to 750W) and at the time get a stable clock speed that gives me a minimum FPS count > 45 with a low FPS fluctuation.

 

 

 

So, my approach is the following:

 

 

 

Power limit Is the max power the graphic card is allowed to use. And within this limit the card will try to reach max clock speed, and when it then hits the power limit it will throttle down meaning that there is a risk of getting unstable/fluctuating clock speeds as a result.

 

So, if you at the same tells the card to never to exceed 2700MHz above 950mV then you “hardcode” the highest possible stable clock sped available within your set power limit and thereby in “theory” this should  minimize the fluctuation of FPS.

 

 

I have attached the track file that I used Mirage2000 vs SU 33 over Syria.

 

 

 

2 mirage vs su33.trk 1.64 MB · 1 download

Ah, I see. I'm no specialist by any stretch either, but that makes sense in the context of staying under PSU limits.

 

Unfortunately I don't have the Mirage module. 

[EightyDuce]

7 minutes ago, jnr4817 said:

How are you finding this +200/1000mhz for the 950 limit? What are you doing to test. I just got an Msi 4090 suprim liquid. Currently all I’ve done is turn the power limit up to 110. However undervolting seems like a good idea and I’d like to extend the service of my gpu. They are like investments now. 

I took what my card was max boosting to stock, which was around 2745 then looked at where it typically settled, which was 2535/2545. I then adjusted the curve so that at +200Mhz which would put me at my max stock boost clock, would max out at 950mV. You have to play with the voltage curve and boost speed. I started at 975 and after testing it was stable, I tried 950. After determined it was stable, I tried 925mV it was stable but would not stay at 2745 and would boost lower. So I left it at 950mv and +200Mhz(2745 effective). Memory +1000 it's a shot in the dark, but was stable;  honestly, could probably go further.

My 4090 is on custom water loop with load temps at around 47C, not sure how much of a difference that makes to the boost algorithm. My card allows for 133% Power Limit and will boost to between 3000-3100, but also draws a refrigerator-equivalent amount of power for a marginal gain in actual performance. I got higher 3DMark scores, but in game it translated into 3-5 FPS at best.

Edited March 4, 2023 by EightyDuce

[jnr4817]

Ok, My card is locked at 110% power limit. I ran the MSI OC test and it gave me +150/200. I am sure it can go higher. Just need to experiment.

THanks

[Panthera_Tigris]

I am running my 4090 FE at 975mV@2750MHz with +200 core and +1300 VRAM. Haven't touched the power limit.

Waiting for my 7950X3D to arrive before I tinker any more. 

[CMDR Shepard]

В 05.03.2023 в 08:35, Panthera_Tigris сказал:

I am running my 4090 FE at 975mV@2750MHz with +200 core and +1300 VRAM. Haven't touched the power limit.

Waiting for my 7950X3D to arrive before I tinker any more. 

You forget about your signature  Still says 1080Ti

[Taterbootz]

I run mine at 100% voltage, +100/+200, and 95% power limit and a custom fan curve.  Usually between 60 and 90FPS, ocassionally dropping to mid 50's with whats in my sig.   I havent checked average power draw, but peak is 454w on the GPU. 

[SneakyBastd]

I haven't messed with voltage curves, just set my power limit to 72% and mem to 12000. It barely drops any performance and uses 100w less power.

I might try what you suggest later though.

Edited October 6, 2023 by SneakyBastd