I’m hoping you could point me towards some resources regarding PPT, EDC and TDC Limits for a new 7950x system I’m building. I’m using Optimum’s guide for undervolting my two 7950x’s: https://youtu.be/FaOYYHNGlLs?t=393
The problem is that on my MSI board, you can dial in individual PPT, EDC and TDC but if you don’t enter a manual number for either of the three, the ones that were not altered stay at “auto” settings. That’s how I have one of my systems set up and it works great! Unfortunately, with my new AsRock Taichi x870e all the numbers have to be entered manually otherwise they stay at 0. I tried booting up the system with the EDC and TDC at 0 and got a whopping 550 Mhz frequency. Also, despite Optimum’s very useful guide, his EDC and TDC numbers… don’t seem right or at least, I’m not understanding them properly. I’ve been searching around the internet to try and figure out any information about how to properly set these numbers and how they affect the performance of the CPU but it has been a surprisingly difficult task. Though I would say I’m more tech savvy than the average person, I am still nowhere near as proficient when it comes to esoteric knowledge about CPU voltages.
So, in conjunction with the negative off-set, I would also like to manually dial in the PPT, EDC and TDC limits to further enhance my system and reduce the thermals. I also watched Der8auer’s video here about the PPT limit scaling here: https://www.youtube.com/watch?v=-sDDA_2USwg
which I found very useful, but, still no information on how to properly set the other two variables. So, if anyone knows of anywhere I could educate myself on such matters or if you have a video explaining such things that I haven’t stumbled upon yet, especially pertaining to the 7950x CPU, I would be very grateful.
Just keep EDC and TDC at stock. The 7950x is a 170W TDP CPU so stock values are 160A TDC and 225A EDC. The default PPT is 230W but you can adjust this as desired to reduce thermals, noise, and power consumption under load.
Trim PPT to set your thermals. Trim TDC and EDC down til you /just/ touch them or get very near it.
Then start on Curve Optimizer. Ryzen Master has the ability to step through all the cores to determine starting values, but especially on a 16c chip it takes some time; easier and faster to just set a negative CO value and jump by 5 til it breaks something, then back it off to the lowest stable value you found.
Lots of the YouTube types even with 9000 still default to “set everything to motherboard limits and then set a temperature limit” which is a level of backwards I can’t quite understand.
Yeah, or just base off 105 or 120 W eco mode. In my experience there isn’t an exact TDC or EDC answer for a given PPT. Sometimes different motherboards set slightly different things anyways and AMD doesn’t seem to spec the values anywhere.
Just a note that YMMV. FWIW, Ryzen Master thinks the 9900X I’m working with at the moment is stable to -34 all core but it’s not stable at even -10. With Zen 3 cores I’ve run that were actually stable in the -8 to -11 range offsetting all the cores didn’t move the benches compared to not bothering with the curve offsets.
This is likely what I was going to do if I couldn’t find any information on how to tinker with the TDC and EDC. It’s how my MSI board is set-up and it work’s great, however, I’m also curious if there’s any value in tweaking the TDC and EDC values in conjunction with PPT.
I heard that for TDC and EDC it’s not just a diminishing return on uping the values like the PPT but more of a sweet spot that work for with what the PPT is set at. Is this true? There’s a guy who did this with the 5950x (I think) here: <link redacted for reasons, I guess>
where he talks about testing the TDC and EDC values but, this is obviously done on a different CPU and with a different mobo. In fact, that would be my other question, if say, I found a video, or chart, or whatever of optimizing the 3 variables, would that data be applicable to my set-up if it weren’t the same mobo? Or if my silicon lottery was different?
So, I guess, I’m wondering if anyone here knows of any resources on HOW to figure out optimum settings for the TDC and EDC for the 7950x or if the only realistic way to do it would be to trial and error your way through your particular set-up.
I found enough in that “low” range (-8-12) with Zen 3 that it was fairly noticeable (~200mhz), but pretty much exclusively under “max load” scenarios; anything that wouldn’t hit PPT in the first place wound up largely unaffected by it. There’s a fair bit of interplay between the limits and what the CPU will actually try to do as well; more TDC/EDC doesn’t guarantee added performance (and seems to regress further the more headroom you add), but slight changes to it can also change what CO tweaks you can get away with.
Ryzen Master has monitoring of what % of each limit you’re “using” at any given time; I’d generally go off it, and aim for 95-100% “usage” of one or both under an all-core workload.
Oh ok. I have Ryzen Master installed on the test bench but, honestly, I’m completely new to using it. I’ll have to watch a few tutorials and get back to you.
When I did a quick search I couldn’t find anything official but I did find the same figure cited in a couple of fairly well respected reviews so I just went with it.
That would depend on what you consider optimum.
If you’re just looking to improve thermals then I’d probably just stick to adjusting PPT alone. If you’re going for more extreme power savings and are willing sacrifice boost and/or all core clocks then there are values for EDC and TDC that AMD recommends for ECO mode.
There’s a lot of variation in setups, BIOS changes etc. so you’ll probably need to setup your own testing to find what’s optimal for you. I suspect limiting current may impact clocks with lightly threaded workloads that are well under the PPT but I haven’t tested. Limiting current may also prevent the PPT from ever being reached with some all core workloads that may lead to less than optimal performance.
Also I had stability issues tweaking EDC and TDC so you may need to set these with curve optimizer at zero because it might affect the offsets you can reliably hit.
Haha, that’s actually a good question now that I think about it! I do some multi-core work including 3d and video editing, but alas, my roots are in being an angry, try-hard, competitive gamer. Plus I use 2d editing software that stands to benefit from single-core performance as well.
So, I guess there’s no real specific focus point that I’m trying to aim for. I need a system that’s good at everything. Of course, I realize that there’s no such thing, so… If I had to call it anything, I would say that my goal is to build as balanced of a system as possible. This means getting the most out of the silicon lottery I may have gotten in single core boosts, while keeping the temps down so the CPU isn’t sitting at 95C and making it as efficient as possible in the multi-core work.
I know a few of these things are at odds with each other, but if I had to prioritize anything I would lean more towards lowering thermals and maximizing efficiency than getting those massive single core boosts. For my other system, I basically have a Curve Optimizer set to -30 on all cores and just the PPT adjusted to … 185, (I think) leaving the other variables on stock and that system runs cool, efficient and close enough to advertised spec that I don’t mind losing 50-100mhz of the max boost. I don’t think I would go so far as to activate ECO mode, though admittedly, I’m not super sure how much of a performance hit it gives compared to manually tweaking Curve Optimizer and the TDP (Is that the right term to encompass the PPT, TDC and EDC?).
For this system, what I’m thinking about doing is to do all of the above and try to tweak the TDC and EDC and maybe play around with Auto-OC, maaaaybe. Do you think that would worthwhile? Is there anything you would do differently?
I have the Curve Optimizer dialed in already, but you would recommend to turn it to stock values and try and figure out the TDC values first, then apply the off-set?
Yeah, I’m in a similar boat. I need to keep temps down because I use a small case and like to keep it quiet. If anything I’d probably look to increase current over the defaults because as long as it stays below 120W I’d like all the performance I can get but I haven’t found performance is lacking so far, so I just stick with the defaults.
If you’re limiting current you may run into issues. You may also be fine though… if you run into stability issues but still want to explore lower current limits just be aware that you may need to find new curve optimizer offsets.
I’m still a bit new to the terminology. When you say “current” are you referring to the PPT, TDC and EDC? Or is it something else? If you were to do this? What parameters would you adjust?
Jeez, I gotta watch a few more videos on electrical engineering because “current”, “amps”, “watts” and their relationship to one another is still one hazy mess to me. I feel like I’m just changing numbers at random without ever understanding what they actually do.
I’m pretty sure you can just tinker with EDC and TDC without worrying about it too much because motherboard default limits are sometimes just set to silly high values effectively just feeding the CPU whatever it asks for in terms of current.
When I’ve watched the values in hwinfo current also never seems to be the limiting factor… maybe some crazy avx512 workload might push it higher but I’m usually just tuning for video encoding which hits PPT first.
Yeah, I got +180 MHz headline with a 1 W reduction in power. A whole 0.7% efficiency gain, woo.
P = VI here. Power, W = (volts, V) * (current in amps, I).
With dual CCD Zen 3, 4, and 5 I usually see PPT limited with a few cores hot, transitioning to EDC limited somewhere around the eighth core. Doesn’t have to be SIMD but since I write AVX and AVX-512 kernels I do tend to be looking at those.
All other people I’ve seen who have adjusted these setting have much smaller numbers, though admittedly those have mostly been 5950x’s and lower CPU’s. Is it the mobo, the CPU or the program that dictates these?
Can I potentially deal damage to my components if I set these too high?
1000 amps is arc welder territory. It effectively just means unlimited.
PPT, EDC and TDC are just limiters that don’t have any effect until the limits they set are reached at which point they cause the CPU to throttle preventing the limit from being exceeded.
If set high they just won’t have any effect because some other limiter will kick in… even if you crank all three you’ll just run into the thermal limiter.
