[SOLVED] What's the relationship between cpu clock speed and cpu voltage?

[mohsenz200]

Hi everyone
I've recently bought a Ryzen 7 3700x and I want to overclock it. In order to overclock I use Ryzen Master software. In the manual mode there is two options. Cpu clock speed and cpu voltage. The default values are 3600 for clock speed and 0.98125 for voltage.
I need to know if these are safe values and of I want to set the clock speed to something like 3700, 3800, 3900 and 4000, what value should I set for voltage respectively? Is there any relationship between them?
Please help.
Thanks in advance.

 

[Math Geek]

voltage is the power needed to run the chip. higher the speed, the more power it will need. they are related in that way.

honestly enabling PBO and leaving it to do its thing is the easiest way to get the best OC. i've yet to see any reviewers able to beat what PBO can do automatically. but if you just want to play around with it. start at stock voltage and up the speed until it won't boot/run anymore. then bump the voltage up one step in the bios. bump the speed again until it crashes/won't boot, then up the voltage another notch... and so on and so on....

every chip can take different voltages and speeds and every motherboard can provide only so much. so there really is no way to tell what your max might be. you're looking for the highest speed with the lowest voltage possible. eventually no matter what extra voltage you add it won't go any faster. back it down until you get that max speed of the cpu with the least possible voltage. also note that with extra power comes extra heat so top quality cooling is a must as well.

you can look around some oc forums to see what kind of voltage others have used with your mobo but i don't recall off the top of my head what i have seen others use. in the end as i said above, i've not seen anyone do better than PBO anyway to justify the time and effort..

 

[Karadjgne]

Ryzen are dynamic cpus. They don't have a set voltage as such. With running a single core, they boost as high as possible with upto 1.5v, but with multiple cores, that boost isn't as high and voltages are lower, somewhere around 1.3v.

That was a huge misunderstanding with the x600's as popular as they were, ppl were overclocking with a static voltage, and burning out the cpu. The problem with the OC was games tend to have a master core, and supporting cores, so single thread is still important. Then ppl OC'd pushing for max boost speeds on all cores, and the overall voltages were too high. And fps suffered since single thread performance took a nose dive.

My 3700x gets better cinebench single and multi core scores with a 4.29GHz all core boost at 62°C than it does pushing a 4.4GHz all core boost at 82°C.

I'm not a fan of Ryzen Master OC. It attempts to OC a Ryzen like it's an intel cpu, and thats not kosher. You'll get better performance by treating the Ryzen AS a Ryzen, and making it more efficient. Undervolt instead, keep the temps down closer to 60ish °C and you'll boost higher on more cores for longer and still maintain single thread performance. That means higher fps.

 

[CountMike]

Hi everyone
I've recently bought a Ryzen 7 3700x and I want to overclock it. In order to overclock I use Ryzen Master software. In the manual mode there is two options. Cpu clock speed and cpu voltage. The default values are 3600 for clock speed and 0.98125 for voltage.
I need to know if these are safe values and of I want to set the clock speed to something like 3700, 3800, 3900 and 4000, what value should I set for voltage respectively? Is there any relationship between them?
Please help.
Thanks in advance.

Those are underclock speeds, only at 4300MHz+ at manual ratio settings you can talk about any overclock. Ideally and providing good cooling, at full load you would want to keep voltage at or bellow 1.35v.

 

[mohsenz200]

I thank everyone who helped me on this. I'm not sure if I can continue this thread with my questions or not. I ask anyway.
I use the stock cooler for my CPU and in full load the frequency reaches to almost 4100Mhz and temp reaches to 79 degrees and the voltage is 1.4v.
The PBO is enabled.
So I set the clock ratio to 39.00 in the bios settings and now the frequency is locked to 3900Mhz and temp is below 70 degrees. somewhere around 66-68. and the voltage is automatically set to 1.1v.
I'm not sure if I did the right thing.
So I need to know what I can do to use my CPU in higher speed. Do I need just a better cooler?

 

[Karadjgne]

Amd (in its wisdom 🙄) placed into bios 2 places for OC. You can literally have PBO enabled in one place and disabled in the other. Genius. In the OC sub menu, if you enable PBO it'll offer an option to raise boost clocks upto 200MHz over stock.

What PBO does and realistically all it does is raise the amperage limits on the PPT, TDC, EDC settings set by AMD.

The cpu wants to stay close to its 65w use, might hit as high as 90w or so, so raising that limit to 1000w does exactly Nothing. PBO is essentially useless for higher tier cpus.

View: https://youtu.be/B7NzNi1xX_4


You have a Ryzen, not an intel. With Intel you set the OC limits and the cpu goes there unless thermally throttled, and doesn't care about its health, temps etc and will easily hit 100°C +.

Ryzens care. It won't let you set settings that'll hurt it. It'll give you the best performance it can within its limits. It's governed by voltages, amperage, loads and temps. You can have the same setup on 2 pc's, same OC settings, same loads and get better performance because one cpu runs cooler than the other. Or have 1 pc with higher performance because it's voltages are lower.

With Intel, performance is based only on clock speeds, coolers are used to keep temps within safe limits. With Ryzen it's not. Safe limits are already established, coolers are used to raise efficiency, which allows the cpu to boost higher, for longer, with more threads.

Throw out anything you think you know about OC, that's based on Intel behavior and simply does not apply to Ryzen.

 

[CountMike]

I thank everyone who helped me on this. I'm not sure if I can continue this thread with my questions or not. I ask anyway.
I use the stock cooler for my CPU and in full load the frequency reaches to almost 4100Mhz and temp reaches to 79 degrees and the voltage is 1.4v.
The PBO is enabled.
So I set the clock ratio to 39.00 in the bios settings and now the frequency is locked to 3900Mhz and temp is below 70 degrees. somewhere around 66-68. and the voltage is automatically set to 1.1v.
I'm not sure if I did the right thing.
So I need to know what I can do to use my CPU in higher speed. Do I need just a better cooler?

Yes you need a much better cooler to get full performance with auto boost. With manual cčpck settings, temps unless they reach tJmax (90c) do not slow it down but at 39000MHz you are loosing 25-30% of possible performance that would be on auto + boost +PBO at temps up to 70c,

 

[Karadjgne]

Yes. By setting hard limits, you apply that limit to single thread clocks as well as multi-thread clocks. With games using a master/supporting threads (CSGO uses just 2 threads for instance) you severely limit single thread performance. Fps goes down.

It's a balancing act. Cinebench or TimeSpy are the best tools to use. Forget about what the exact OC numbers are, what you want is single And multi thread scores to go up. If single drops off but multi goes up, you loose performance. If multi drops, but single goes up, you lost performance. Doesn't matter what the core frequency is, if it's 3900 or 4400 or anywhere in between, it's the balance between single thread performance and multi thread performance. That's Ryzen OC. Not the GHz, but making the cpu as effective and efficient as possible so it uses what it has to best advantage.

 

[Karadjgne]

From what I can gather, and this is unsupported but I did read something on this somewhere, seems Intels have a static IPC. Crank them up faster means more clock cycles, better performance. Ryzen are different. They seem to have a slightly variable IPC, that drops with temp increase. From what I read, as temps start climbing above 60°C the transmission speeds between the various chiplets start slowing down. Meaning as you crank up the GHz, and the resultant temps and voltage, you actually start loosing performance on single thread.

That supposition result is supported by various testing done by multiple others, including pro reviewers and myself, as TimeSpy and Cinebench results with higher OC or boost levels show lowering single thread results with higher temp outputs. This can affect multi thread workloads as evidenced with my own pc. I get better scores and resultant fps with a 4.29GHz all core boost at 62°C than I do with a 4.4GHz all core boost at 82°C. Single thread scores dropping as well.

Take that as you will, but keeping a Ryzen cooler will have better results. The stock cooler does just fine, it's about the same ± as a CM Hyper212 Evo in ability, but doesn't offer quite the same overall quietness at its maximum.

 

[hotaru.hino]

The PBO is enabled.
So I set the clock ratio to 39.00 in the bios settings and now the frequency is locked to 3900Mhz and temp is below 70 degrees. somewhere around 66-68. and the voltage is automatically set to 1.1v.
I'm not sure if I did the right thing.
So I need to know what I can do to use my CPU in higher speed. Do I need just a better cooler?

Something of note is that the power dissipation, and thus heat generated, is generally summarized by the formula P = C * V ^ 2 * f, where P is power, C is capacitance (for our purposes, we can ignore this value), V is voltage, and f is frequency. As you can see, voltage affects the power dissipation by a power of 2, so even a small change in voltage can have a dramatic effect on power dissipation. For instance, if you started with a voltage of 1.0, moving it down to 0.9V now causes voltage to only contribute 0.81. Moving it up to 1.1 causes it to contribute 1.21.

Otherwise, setting a fixed clock speed effectively makes PBO worthless. PBO is meant to change the boosting behavior, and since the CPU can no longer change its clock speed (outside of maybe thermal issues), the feature won't do anything. And if you want the CPU to boost at a higher clock speed, you will need to start by using a better cooler, as temperature does dictate a lot of the boosting behavior.