AMD 9900X Undervolt and what I found.

[wade7575]

As many of you know on this forum I got an AMD 9900X CPU ASUS X870E ProArt Mobo and an Intel ARC A580 card.

I wanted to stay with air cooling for this build and choose the new Noctua NH-D15 G2,I tried the Thermalright Frost Commander and it was just to loud and when the Noctua was gifted to me I said bye bye Frost Commander,I will say that the Thermalright cooler performed as good or close to what the Noctua did and with the Noctua's I think it would be a great cooler.

I was going to try just limiting the voltage the cores could get by Undervolting them by just lowering the voltage and nothing else as I was told this would work and it was a massive flop.

I instead got help from a person on another forum and I adjusted the PPT/TDC/EDC and made a few adjustment's in Curve Shaper and Curve Optimizer.
The stock CPU power limit setting's according to AMD are as follows.

PPT 162W
EDC 180A
TDC 120A
Total Watts shown in Armoury Crate are 162 Under load when running handbrake.

Running Handbrake and with only EXPO1 Enabled these are the temps I got with HWInfo and Armoury Crate and encoding speeds I got it FPS according to Handbrake.

Encoding .265 TV Show 643.69 AVG FPS temps were 68C to 71C and it mainly ran around 69C to 70C for most of the encode and would hit 71C.

Encoding .264 MP4 TV Show 1106.02 AVG FPS temps were the same.

With changes to the Bios.
PPT 130W
EDC 165A
TDC 105A

In Curve Shaper I applied for Medium and High parts of the Curve Negative 15,for Medium it has a Low Medium and High part and all 3 were set to Negative 15,the same goes for High it also has a Low Medium and High that need to be adjusted that Negative 20.

I then went into Curve Optimizer and applied an All Core -10

These are the AVG FPS I got in Handbrake and temps with the new Bios settings.

.265 TV Show AVG FPS 618.51 temps 53C to 55C,the CPU hit's hits 55C about 1/3 or less of the way threw the encode and never moves from there.

.264 TV Show AVG FPS 1083.71 the temps are the same for .264

I'm very happy with the drop in temperature's that I got vs the performance loss when encoding video which is almost nothing,I meant to record the encoding times but I forgot to but it's 10 to 20 seconds or so longer at the most.

I did the math at 70C stock settings and with the Bios setting's went to 55C for a 15C drop in temps and as far as I'm concerned almost no loss in encoding speeds.

When compared to my i9 9900K and GTX960 the encoding speeds for .265 were around 250 to 320 FPS and 320 to 450FPS for .264 and with .264 I normally seen around 400 to 420 FPS my new PC is extremely fast.

My main reason for wanting to Undervolt this system and wasn't to reduce power to save money on my hydro bill,the main goal was to keep the CPU running as cool as I could with as little impact to the performance of the CPU when running Handbrake and other heavy load programs as well.

I have always believed the better you treat and look after your stuff the better it will treat you,and for me I couldn't care less if these CPU's were meant to run at 85C all day long I'd rather not push my stuff that hard.

Another reason for doing the Undervolt is I knew before buying my 9900X it would run warmer then my i9 9900K and I had a gut feeling the Ryzen 9000 Series would run a bit cooler then the last gen of AMD CPU's,when I seen that my 9900X was running at 71C when using Handbrake which puts the most load on my system out of all the programs I use I wanted to reduce the temps because it nots warm where I live at all right now but when summer hits I didn't want my CPU running 85C to 90C as it gets really humid where I live,I'm hoping at the hottest points in the summer where I live my CPU may get to 70C to 75C Max but I'll have to wait and see for that.

 

[wade7575]

I forgot to include my Cinebench scores and temps for this review and here they are,I only did the Multi thread test.

Stock settings the score was 30794 and the temps were 51C to 54C during the test the 9900X ran at 51C to 52C

With my Bios settings the score was 28863 and the temps were 50C to51C and the CPU never went past 51C during the testing.

Handbrake for sure puts more of load on the CPU over Cinebench and I thought it would be the other way around because I have never ran Cinebench before other then a few times to stress test a PC that was brought to me to that was having problems.

 

[Bond007]

I am glad to hear that you were able to get results you are happy with. Nice temp drop.

If you have the time I would love to hear what the performance differences may be with one slight change.

Leave all of your negative offset values the same, put PPT/EDC/TDC to stock, change temp limit to 55 (platform thermal throttle limit?). Run tests.

 

[gingerbee]

Very cool thanks for sharing, it's for sure a lot harder than a simple negative offset of voltage, but these chips are so different in their power delivery/regulation than chips of the past. to be honest I kind of like how simple it used to be.

 

[Shadowarez]

increase FSB OC achieved

 

[wade7575]

Very cool thanks for sharing, it's for sure a lot harder than a simple negative offset of voltage, but these chips are so different in their power delivery/regulation than chips of the past. to be honest I kind of like how simple it used to be.

Once I had a baseline for the numbers to enter into the PPT/EDC/TDC it wasn't hard at all,I used HWinfo to watch the EDC/TDC numbers.
I started with 88W PPT which I knew would be to low and also went with the suggested lower EDC/TDC numbers as well and raised them all at the same time.

Once I settled on 130W for PPT I watched the EDC/TDC numbers more closely and set those numbers so they were running at 80%,the PPT always runs at 100% under full load as that's the number that limits that the total amount of Watts going to the CPU under full load,I don't know for sure if leaving the EDC/TDC so they are at 80% is the correct way to it as that was never mentioned,I just know from reading about EDC/TDC is also power delivery at different points other then full load so I didn't want to bottleneck them I felt I should leave a bit headroom.

 

[wade7575]

Just one update to my testing the encoding speeds for .265 I stated in my finds were correct but I didn't make one thing clear about the resolution which maybe helpful to some people.

I normally encode everything to 720x404 for tv show because the size I download them in and I want to reduce the megabyte size,I also do legit encoding jobs from time to time like wedding videos and stuff like that as well.

With the .265 the original file resolution was 1280x270 and encoded to 720x404 and I got 643 stock bios settings and with my new bios setting got 618.

When encoding the same .265 file at the same resolution of 1280x720 to 1280x720 to just reduce the megabyte size I got 360 FPS with my changed settings I didn't bother to go back and reset my bios settings.

 

[wade7575]

I'm going to do the testing that Bond007 has ask me to do when I get a chance do it.,

 

[wade7575]

I just retested the way bond007 asked me to I put PPT/TDC/EDC to stock I left Curve Shaper for the Medium part of the curve at negative 15 and for the High part of the curve I left it at negative 20 and in Curve Optimizer I left it at negative 10 All Cores.

For anyone who hasn't used Curve Shaper it hard to explain and I will,there is a Low Medium High and Max part of the curve and for section there are 3 points that need to be adjusted.

This is what it would look like in the bios.

Medium-Low 15
Medium-Medium 15
Medium-High 15

Low Medium High and Max all have 3 point that can be adjusted and there's 4 points to the curve overall there the Low Medium High and Max and within each there's 3 point to that one small section of the curve.


There were my finding's running Handbrake to test temps and encoding speed changes.

50C Max temp limit test
The CPU ran at most of the test at 39C and use 94Watts on AVG
about half of the cores ran at 3892mhz the other half at 4482mhz
the encoding time for a 1:06:21 took 1:48 minutes


60C Max temp limit test
The CPU ran at most of the test at 49C and use 125Watts on AVG
about half of the cores ran at 4872mhz the other half at 5108mhz
the encoding time for a 1:06:21 took 1:32 minutes

With bios settings restored to my custom settings PPT 130W EDC 165A TDC 105A and Curve Shaper and Optimizer were set at what's mentioned above.

The CPU ran at 51C for half the test and then reached 53C and use 130Watts on AVG
about half of the cores ran at 5096mhz the other half at 5200 to 5400mhz
the encoding time for a 1:06:21 took 1:30 minutes

I don't know how to describe it other then to say that my PC boots up faster with my custom bios settings and also runs faster for the most part except for the 60C test and my custom bios settings when running Handbrake.

 

[Bond007]

Thanks for trying, but also weird results .

It doesn’t make sense why the cpu is not going to the EXACT temp set as the limit…AMD CPUs are very accurate with it, and you should definetly be thermally limited with those settings. Something doesn’t make sense. Hmmm.