[SOLVED] Reducing PPT while keeping stock EDU and TDU

Apr 30, 2021
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I've bought the Ryzen 5900x CPU and its temperature peaks are too high. So I decided to do undervolting and reduce the PPT to reduce the overall power consumption and temps. After doing that, the temperatures much more reasonable.
The default PPT is 142 and I lowered it to 110 (with the undervolting, the temperature is much more reasonable, and the score of Cienabench 23 almost the same as stock).
I run stress tests for multicore and single-core, gaming, heavy tasks, for hours and it seems to be stable...

I'm not looking for additional improvements, I just want to confirm it wouldn't harm the CPU by reducing the PPT but keep EDC / TDC with stock values.
 

iPeekYou

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It's alright. The values shown are the limits, i.e. if you're not hitting the limits the boost will continue to climb. In fact, PBO ECO works the same way by deliberately reducing the limits to cut on power consumption. If anything, boost clocks will be hurt and some stock performance as well, if the limits are reduced too much.

Longevity won't be hurt, it's too much current, heat, or voltage that'll kill the chip. Too much current causes dielectric breakdown, too high voltage causes electromigration (might got them backwards, I forgot). Heat is a well-known limit as well. Your configuration indirectly cuts on current and voltage through power limits, so no worries.

Stability won't be affected as far as I'm aware since that's usually tied to voltage and/or temps. Voltage is managed automatically by the motherboard in PBO enabled conditions, and temps managed by you, in part, with cooling solution of choice.

TDC is the limit of current that motherboards use in thermally-constrained circumstances (or the maximum sustained current), EDC is limit of current for peaks (i.e. burst conditions).

On the other hand, raised PPT limit is usually used to alleviate power limits on heavy multithreaded workloads, especially apparent in high core count processors such as yours. Stock or reduced limits are limiting performance in such load, but user's mileage may vary so custom PPT limits can be beneficial to users. If there's no noticeable performance decrease, then no problem.

TL;DR: no need to worry. If performance and stability is acceptable, then no harm no foul.
 
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iPeekYou

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Jul 7, 2014
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It's alright. The values shown are the limits, i.e. if you're not hitting the limits the boost will continue to climb. In fact, PBO ECO works the same way by deliberately reducing the limits to cut on power consumption. If anything, boost clocks will be hurt and some stock performance as well, if the limits are reduced too much.

Longevity won't be hurt, it's too much current, heat, or voltage that'll kill the chip. Too much current causes dielectric breakdown, too high voltage causes electromigration (might got them backwards, I forgot). Heat is a well-known limit as well. Your configuration indirectly cuts on current and voltage through power limits, so no worries.

Stability won't be affected as far as I'm aware since that's usually tied to voltage and/or temps. Voltage is managed automatically by the motherboard in PBO enabled conditions, and temps managed by you, in part, with cooling solution of choice.

TDC is the limit of current that motherboards use in thermally-constrained circumstances (or the maximum sustained current), EDC is limit of current for peaks (i.e. burst conditions).

On the other hand, raised PPT limit is usually used to alleviate power limits on heavy multithreaded workloads, especially apparent in high core count processors such as yours. Stock or reduced limits are limiting performance in such load, but user's mileage may vary so custom PPT limits can be beneficial to users. If there's no noticeable performance decrease, then no problem.

TL;DR: no need to worry. If performance and stability is acceptable, then no harm no foul.
 
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Apr 30, 2021
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Thank you for the comment. The reason I posted this is exactly the PBO ECO. With PBO ECO they reduced the PPT to 88W (IIRC) but also reduced the EDC and TDC to lower numbers. I don't want to limit its max current because I don't want to lose performance or change too many stock values (since I believe that AMD knows what they are doing) but to reduce the power consumption limit.

The undervolting (with the PBO Curve Optimizer) did a great job of balancing the voltage per clock speed, and the CPU is stable with lower temps. But also, it caused the CPU to overclocked itself until it reached its limit power consumption, and all the thermal improvements are kind of gone :D.

So I wanted to also limit this "extra overclocking" by limiting the total power consumption since it already uses higher clock speeds thanks to the undervolting, and I don't really need additional power, but just controlling its thermals... But when I saw the ECO mode reduces also the EDC and TDC in addition to PPT, I was a little bit worried and wanted to confirm that using their stock values (140A and 95A) isn't a bad thing if I use lower PPT...
 
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Apr 30, 2021
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Not a criticism...just out of curiosity why not upgrade your cooling ?
Fair question :D. I already have the Dark Rock Pro 4 as a CPU cooler. While gaming the CPU can reach 85C (stable) and even 90C (spikes). This is OK for this processor, but I don't like it :D. With undervolting and reducing PPT, I don't lose performance in benchmarks, while keeping it cooler by 10C-15C - this is a huge difference. And, if that CPU is stable with lower voltage why not reduce the power consumption?

The DRP4 is an excellent cooler, and I doubt if replacing this high-end cooler with another one can achieve such a difference...
 

iPeekYou

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Fair question :D. I already have the Dark Rock Pro 4 as a CPU cooler. While gaming the CPU can reach 85C (stable) and even 90C (spikes). This is OK for this processor, but I don't like it :D. With undervolting and reducing PPT, I don't lose performance in benchmarks, while keeping it cooler by 10C-15C - this is a huge difference. And, if that CPU is stable with lower voltage why not reduce the power consumption?

The DRP4 is an excellent cooler, and I doubt if replacing this high-end cooler with another one can achieve such a difference...
I can see how limiting PPT would help, if your DRP4 can't get it to small 80s, there isn't much else short of custom loop. It's pretty much at the top end of air coolers AFAIK.
 
Apr 30, 2021
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I can see how limiting PPT would help, if your DRP4 can't get it to small 80s, there isn't much else short of custom loop. It's pretty much at the top end of air coolers AFAIK.
True, but I'm getting these temps only while gaming. In Cinebench for example, I'm stable on ~70C.
My suspicion is that the heat from the GPU raises up while gaming, and harming the efficiency of the DRP4 air cooler...

Maybe adding more/better case fans will help to reduce it even further, or even AIO/custom loop, but I don't think it will reduce the temps like that with stock values.
 

iPeekYou

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True, but I'm getting these temps only while gaming. In Cinebench for example, I'm stable on ~70C.
My suspicion is that the heat from the GPU raises up while gaming, and harming the efficiency of the DRP4 air cooler...

Maybe adding more/better case fans will help to reduce it even further, or even AIO/custom loop, but I don't think it will reduce the temps like that with stock values.
If you're keen on reducing the GPU temps as well, you can try slapping an AIO on it. As can be seen on my sig, I've got one and even though it's just a 120mm, it manages to keep my GPU at 47 under Kombustor. In gaming I see 41 at maximum. Bonus point for taking heat away from near the CPU.
 
Apr 30, 2021
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If you're keen on reducing the GPU temps as well, you can try slapping an AIO on it. As can be seen on my sig, I've got one and even though it's just a 120mm, it manages to keep my GPU at 47 under Kombustor. In gaming I see 41 at maximum. Bonus point for taking heat away from near the CPU.
No, actually not. I'm just want to keep the CPU around 80C, so it's good. I just wanted to know if the EDC and TDC can be kept as stock...
 

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