Should I limit PBO settings at all if cooler/etc keeps up?

Nazo

2[H]4U
Joined
Apr 2, 2002
Messages
3,643
So I just wanted to make a quick check. Is there any reason I should limit any of the PBO settings as long as the cooler and everything is keeping up?


To explain more specifically, basically I have a pretty good third party cooler and my CPU is underclocked just a little (5600X with max boost set to -250 so it maxes at 4.4GHz -- this puts it on the good side of the voltage increase curve before it goes up exponentially from >4.4 up to the full boost of 4.65 so it stays super cool and hopefully will last me a very very long time.) In a worst case scenario (namely Prime95 small FFTs) it hits about 74C, maybe 75C peak, so this is well below the margin of 80C that is considered best if you want a modern CPU to last a really long time. Of course, temperature is not the only consideration and it still draws a LOT of power in that small FFT test of Prime95 (around 114 watts or so total.) Now, I basically generally want the CPU to perform at its best most of the time and I do rarely do a few things that can actually max it out (such as encoding -- yes I realize Prime95 is not a good real life example, but encoding in particular does push it just about as hard) and would rather it wasn't limited if at all reasonable to keep it this way. However, I note that I have very definitely had to exceed the stock PBO values for it to be able to max out like that at 4.4GHz. For reference, these are the PBO values:
Stock: PPT: 76 TDC: 60 EDC: 90
Motherboard: PPT: 1000 TDC: 160 EDC: 190

Obviously the motherboard limits are set ridiculously high. I presume the point there is to effectively disable precision boost caring about any sensor but temperature since no CPU existing today could ever hit those numbers with, I guess, a simple sanity check in regards of if something were ever made that could it would hopefully not fry the board instantly. Using this "unlimited" profile, I watched the actual usage values while Prime95 testing and thought I may as well at least set some "sane" limits in case something ever goes horribly wrong so the CPU can't just fry itself if somehow it could actually go over reasonable values and put them where each would hit apx 97-98% the maximum values I got in Prime95, so I ended up on these values:
<=98%: PPT: 117 TDC: 79 EDC: 108
This way with something pushing the CPU as hard as normally possible it never exceeds any of those values, but if something could theoretically push any of those values even higher it should start to limit things rather than going all out as the motherboard settings would allow. I'd be willing to bet good money if something could somehow push the numbers the mb limit sets it would fry this CPU. But is that even possible even if something somehow went wrong -- say an infinite loop or something? Will any of these ever limit me in some way while using the CPU in a sane manner even though they were set above what Prime95 going all out produced?


Anyway, my question here is fairly simple otherwise: should I be setting any of those down any from those values I came up with? I've tried to understand them and sort of have a basic idea, but still don't 100% understand what each truly means in regards to how it affects the performance boost. Should I be limiting EDC below the result I got when it was unlimited to reduce total amps, for example? I'm still unclear on exactly what TDC translates to as well. It's supposed to be "limiting current when thermally constricted," which would sort of seem to imply to limit current as temperature increases, but exactly what this even means I don't know given that the stock TDC value of 60 certainly didn't keep it from hitting 90C in Prime95 on all stock settings. In particular, these numbers are quite a bit above the stock values and I wonder if this can affect the CPU's lifetime greatly. I could potentially need this CPU to last me 5+ years (I hope it doesn't come to that, but I have to work with the possibility it could,) but at the same time, I still want it to perform well, so I really don't want to limit it any more than I have to and I do occasionally do things like encoding where it will actually push the CPU around the same sort of range that Prime95 did -- it's not just gaming. (Gaming, btw, uses far far less power and runs really cool around 41C or so in most, so I presume there is no issue there.) And yes, I'm aware that running anything over stock has potential to affect its lifetime, so I'm having to try to find the right balance here where I get performance in those heavy tasks but it won't die on me too soon.

BTW, my curve optimizer values are pretty low for all the cores but one (-30, -29, -30, -30, -21, -30.) I have read where people were saying that lower voltages do equal more current (I presume that the idea is that the net result is it needing roughly the same amount of power to perform the same, so lower voltage would, of course, mean more current to reach the same amount of power.) However, of course, higher voltages equal more temperatures and temperature goes up fast with voltage on the 5000 series CPUs, so I can't raise them a very large amount before it starts to hold temperature ranges I don't want it to in Prime95/encoding/etc. I have read, and I quote "amps kill" so I do sort of wonder if I might be better off with higher CO numbers (or I guess I should say "lower" to be less confusing) in terms of long term lifetime? Is there such a tradeoff -- or if so, is it enough even to matter? I don't relish the idea of running a bunch of tests and value checking to try to figure out the best balance of voltage temperature for current, but I suppose it would be worth it if it translates to the CPU lasting significantly longer. Would the current possibly be more important than the temperature at these sorts of ranges and would setting those CO values higher translate to actually being a lot better for the CPU or is that just not worth doing?
 
Last edited:

Phazer Tech

Limp Gawd
Joined
Jun 15, 2022
Messages
160
As long as temps are in check I wouldn't worry about the PPT, TDC and EDC values. However something that has given me issues is the fact that most motherboards push PBO frequency to the limits by default. I recommend disabling the additional +200Mhz or +500Mhz or whatever PBO allows you to do, and just set it to +0Mhz. I've found that CPUs will handle the extra boost at first, but then degrade over time and can't handle that extra boost anymore. The default PBO settings are stable, but again, many motherboards don't do this by default which is silly.
 

Nazo

2[H]4U
Joined
Apr 2, 2002
Messages
3,643
Well, I actually have a boost limit set to -250 (I found that the AMD Overclocking section has an option to change it to negative whereas the normal PBO settings do not for some reason.) That keeps it under the point of the voltage curve where the voltage shoots up fast, thus keeping heat manageable. I just didn't want to go into too much detail because if I do the first post is always "you wrote too much. Have you tried doing that thing you said you already did in the second line?" so I tried to keep it short.

I am dealing with an issue that it still doesn't want to boost enough though. The cores are sleeping when a game like NMS tries to do terrain generation for example, so they have to wake up and go up too slowly, thus I get very noticeable hitching in such scenarios. Right now I'm leaning towards sticking with a fixed frequency rather than limiting the boost. (It's still amazingly cool and efficient as long as I keep it low enough that the voltage is good.) I wonder if there is a better compromise between the two?
 

kamikazi

[H]ard|Gawd
Joined
Jan 19, 2006
Messages
1,490
Take a look at my fiasco of a thread involving my 5950x. It suddenly lost the ability to boost all core with load. I had to use PBO to correct it. I can't get stock performance anymore, I have to either accept low all core performance or high all core performance at the expense of more power. Nothing in between. I don't think you're in the same situation as me, but there are quite a few tidbits in there about tweaking PBO that may help you out.

5950x will not boost right
 

Nazo

2[H]4U
Joined
Apr 2, 2002
Messages
3,643
I tried to look over it, but it's three pages of discussing a wildly unrelated issue, so I struggled to find anything relevant mixed in there. What I can say is that -- at least at the more limited frequency I'm using and lowered voltage and all -- my CPU is definitely not running into any limitations I can define at least (I have had another issue that I think isn't CPU related posted elsewhere.) If anything it may be more the other way around. I might suggest you might want to try what I did and do an all core override and manual voltage setting to find the best balance you can get out of your CPU since PBO seems to be limiting you and that basically just bypasses all those limitations (though it does have the side effect of also bypassing the safeties so temperature is potentially dangerous, but you seemed to be ok in that department.)

Is there some specific setting you're saying you've enabled that causes it to jump straight to boost under any sort of load or something? Because that would be great. I prefer to not use software solutions as much as possible though. (Specifically I want to change settings in the BIOS rather than relying on Ryzen Master to force things.) That's not to say software solutions are 100% out the window, just I'd really rather something universal (aka works even in Linux and everything else without me having to run third party software that may or may not be well supported.) Honestly I was disappointed a bit on how much difference it seemed to make between PBO set to run it to 4.4GHz and just simply manually setting it to 4.4GHz. I do definitely feel like the governor was trying too hard to keep the cores low so took too long to scale them up because I did definitely see a noticeably smoother gameplay in stuff like terrain generation with fixed frequencies. If I could bias the governor towards wanting to boost faster that would be great.

Mostly I posted this particular thread less because of any issues and more just to verify that it wouldn't hurt anything to just let it basically run as high as it seems to be capable of in regards to all those numbers.
 
Last edited:

kamikazi

[H]ard|Gawd
Joined
Jan 19, 2006
Messages
1,490
Sorry it wasn't helpful. There was a lot of discussion about PBO settings in there and how they affect performance. I thought there may be a nugget of info that would help you.
 

Nazo

2[H]4U
Joined
Apr 2, 2002
Messages
3,643
That's fine. I get where you're coming from. Just, atm I basically am setting them to not be limiting anything until I'm given some sort of reason to do so.
 

crazycrave

[H]ard|Gawd
Joined
Mar 31, 2016
Messages
1,550
The 5600x can do 4.6 under load if you're looking for more clock speed, that is default mode in Ryzen Master with a dam good cooler and 3600Mhz CL 16 Muskin Redline memory.

 

Nazo

2[H]4U
Joined
Apr 2, 2002
Messages
3,643
I'm not. That's part of why I kept the original post so simple and didn't go into all that. I realize what the defaults are and it took a lot of time and effort to find what I consider the perfect balance, even if it is slightly below the stock boost.
 
Top