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PBO limits for 5900X

Forceflow

Forceflow

Forceflow

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Joined
1 Oct 2020
Posts
60
Need some help with my 5900X + Tomahawk X570 combo. Latest bios, cooler is a NH-D15.

I used to just whack PBO on "enabled" in the bios, which resulted in PPT 500, TDC 210, EDC 280. These correspond to "motherboard limits"
This has been how the system has been running happily for about a month or three. I'm reaching 75C in Cinebench R23 continuous loop. Total CPU power stays at about 145W at full load.

Yesterday I was fiddling some more in the BIOS and discovered there was a *second* place where I could enable/disable PBO.
When I put it on "enabled" there, the limits became PPT 500, TDC 210 and EDC 200. Now my system runs hotter, because the CPU power pushes to 160-170W.

I don't understand? Are the motherboard limits safe? Why does my system run hotter when the EDC limit is *lower*? What should I do?
 
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Id advise to download a program called Ryzen master, then have a look at a video for PBO / CO tuning - You can test the PPT / TDC / EDC from Ryzen master to find out what its pulling under full load and set them to the figures you find, Jot everything down and pop the results into the BIOS (or you can let Ryzen master do it all for you, beware, takes a few hours.

Might seem like a bit of faffing about but its much better for the system to be tuned, you end up running cooler AND faster.
 
Where are you measuring that GHz speed from? Seems low. I'm at stock power limits and boost to 4.95Ghz single core and all core loads are ~4.6Ghz depending if it's AVX or a lighter load. This is with per core curve optimizer.

Also I'm on mobile but I believe there is an EDC bug on the laterest BIOS that limit performance but I'll have to have a proper look later.
 
Forceflow said:
Should have clarified: that Ghz is all-core during CB R23 continuous run.
Click to expand...
What are your cr23 scores?

My all core boost is actually more like 4.4-4.5 having just ran cr23. I thought it was more that that.

My multi core score is 22561.

Either way I think there is a point when too much EDC becomes a negative for performance and the same with any of the PBO parameters.

Just chucking power at these CPU's doesn't seem to get the gains of previous generation CPU's and they really need tuning for efficiency.

I believe as suggested above you can change these on the fly within Ryzen master so you get keep upping EDC as you are running cr23 and watch the clocks change dynamically until you reach the right figure for your set-up.
 
My CR23 scores are low 22k-ish.

Is it dangerous to leave PBO on the default values? PPT 500, TDC 210 and EDC 200.
I'm not much of a tinkerer.
 
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They sound very high to me, I would go with one of the lower 3 in your chart, which ever gives best performance. If you just want to use PBO.

but stock limits with a curve optimizer would be best
 
I'm not sure it was even active, 142w is exactly the stock ppt so I don't know why but maybe 500 is so high it's invalid.

Easy test would be to run stock then your 500ppt PBO and compare scores and temps.

If it really were drawing 500w I'm pretty sure something would catch fire
 
motherboard limits should be set by the mobo maker and should be inline with what the vrm can deliver.
no way your gonna pull 500w ppt on that cpu, best thing is to tune it according to your cooling solution.
im on air cooling with my 5900x and cheapo mobo so i run at ppt 170w, tdc 107a and edc 141a and set temp limit of 85c.
with temp limit in place low core loads wont spike to the 90c throttle limit but will throttle at 85c, thats just what im comfortable with. no throttling occurs on all core load due to temps, its around 83c all core in p95 sfft.
once you find your power limits for the temps your happy with then you can play with curve optimiser to undervolt the cores and test using corecycler for stability. i dont run any monitoring software or anything else when running core cycler so nothing else can cause cpu load to lower boost clock testing.

this is what i got for my co testing:
Code: 
Core    Max Performance Percentage    Max Clocks    curve optimiser negative


0                        174                4950        0
1                        174                4950        0
2                        170                4925        0
3                        166                4900        3
4                        162                4875        5
5                        158                4875        6
6                        145                4700        14
7                        154                4725        7
8                        141                4675        9
9                        137                4650        12
10                      150                4725         12
11                      133                4650         22
 
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Thank you for all the replies!

Up until yesterday, I had appearantly been running it on PPT 500, TDC 210, EDC 280, which I now see are motherboard values that correspond to "let er' rip".
I never minded these values, I thought these were safe, and they probably are, but they are a wasteful way of (not even getting the best, mind you) better performance in all-core loads. I don't understand why just enabling PBO (what an end-user would do, just set it to "enabled" in BIOS) results in these wasteful values.

What I did *not* understand is how my CPU got hotter and got better all-core boosts when I lowered EDC. More limited, less power draw, right? But after watching and reading a lot I now know that there's a certain optimum to tuning these parameters, and how they work together. After continuous tweaking on just the PBO2 params I landed on PPT 180, TDC 120 and EDC 165. This results in an all-core load of 4,35 Ghz at 72 degrees in CB R23.

Since this is mostly a gaming system, I decided against dialing these in, and just went back to stock. The gains in-game are non-existent or very minimal, even in games that like a lot of threads (warzone, darktide). Lower thermals and lower power usage is beneficial for my chip and for the environment, at the moment.

I'll keep that PBO2 profile handy through for when I encounter a situation in which I need more oompf, and maybe have a look at Curve Optimizer later.

My stock Cinebench R23 all-core scores are in the low 22's, but my RAM probably isn't the best (3600 Mhz with 16-19-19-19 timings) and I've read up that recent AGESA versions introduced some odd clockspeed bugs.

Does this all sound reasonable?
 
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ph123uk said:
Sounds about right to me, although i'd be tempted to set per core undervolts to get your temps better too :)
Click to expand...
I hear you :), but my temps are fine as they are now (hardly hit 70 on CB R23 all core), and curve optimizer, while it looks fun to play with - it also looks like a whole lot of work and a can of possible instabilities to open up.
 
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Yea, it can be a little bit of a mine field, to start with i just put "all core" on -10 and it was fine before I went and fine tuned it all - But, if you are happy, thats all that matters :)
 
Forceflow said:
Is -30 all core stable? That's like the max you can dial in.
I also raid that touching the PBO scalar is not recommended, since it can have a dangerous effect on voltages.
Click to expand...

totally stable in my system.
I've been playing about with it so its currently set to 10. Was lower at 4. play about with it to see what gives you best scores etc.
 
Forceflow said:
Thanks man. I might have a look at that. How did you go about the finetuning?
Click to expand...
Sorry for the lazy reply but its essentially this:

GUIDE STARTS HERE
The steps for using Curve Optimizer to OC are:

  1. Curve Optimizer is part of PBO 2.0, so enable PBO and set it to your platform's limits.
  2. Under PBO, leave the scalar at Auto. Auto performed the best for me, but if you want to try to tweak this, I'll mention when you should do this.
  3. In Curve Optimizer, start with an all core undervolt of -5. Iterate between STABILITY TESTING (HIGHLY TRICKY. SEE BELOW.) and lowering this by -5 each time until you find the lowest stable value.
  4. Now you know the undervolt limit of at least one of your cores. You can now go into per core undervolting to find which cores you can bring down further using the same iterative method above.
  5. You're done. Now's the time to test a custom scalar value if you really wish to.

But after doing the above, instead of dropping it -5 I went to lesser digits of -1 etc - But if you cant be bothered with all that testing -10 tends to be good for most people and nets you a little cooler, faster processor
 
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