Adaptive Voltage Overclocking and C States

[VeerK]

Hello ROGers,

I am trying yet failing to understand how Adaptive Voltage should work with my board. I currently use an Asus Hero on Bios 1203. I have used manual to overclock my 4770k to 4800MHz @1.248 Volts stable. However, I have noticed that I have to put 1.224 Volts in the Bios to get a reading of 1.248 Volts in CPU-Z under 100% load, otherwise I idle at 1.232 Volts. These settings under Manual. LC PLL, Low BCLK, CPU Strap 100, Min/Max Cache 4700MHz, PLL Auto, DRAM 2133 MHZ, EPU Disabled, iGPU Disabled, Eventual Input/Output at 1.8V, DRAM Voltage 1.65V, anything not mentioned is set to auto default settings, such as LLC, etc.

When I change the manual to adaptive and then enter the appropriate voltages, save, then boot into Windows, the voltage remains static just like it did under Manual. Someone mentioned that C states need to be enabled from auto, and when I did that the voltages do drop. However, why does Adaptive only work when C states are enabled? I get the same voltage drop if I enabled C states with Manual, so how is Adaptive advantageous at all?

Furthermore, with Adaptive and C states enabled, I notice that my idle/light load voltages jump all over the place, which I think is a problem caused by enabling C states. Raja's guide doesn't cover it and Google is surprisingly mum on the difference. It would be very, very helpful if someone could explain how to set Adaptive up properly on Maximus VI Hero and what the CPU Settings should be.

Thank you ROG Community for your patience and knowledge!

[Arne_Saknussemm]

Hi VeerK.

lets do this in parts. first you have to know that the CPU has a table of voltages preprogrammed into it (the VID table). As multiplier changes with load on the CPU it asks for more or less voltage. this would be the default AUTO behaviour. Also, at load the CPU is programmed to protect itself from spikes in voltage the Vdroop you will have heard of.

Now, there are a number of ways you can change what voltage the CPU receives.

Offset: applies a positive or negative value you define to the whole range of voltages in the VID table...from idle to load

Adaptive: applies a positive or negative offset to only the turbo multipliers

Manual: overrides VID table and feeds CPU constant voltage even if multiplier varies with load!

LLC: overrides Vdroop so when CPU is under load it does not drop the voltage as much as it wants to.

You pay a good piece of money when buying these CPU's for the power management features. i.e. that they turn down the voltage and multipliers depending on the load. These features are the C1E and Speedstep (EIST). other C states are further power management in the form of various sleep states. You want to leave them enabled for all 24/7 OCing. If you disable them you will not get the downclocking you want. C1E is disabled in BIOS and EIST can be disabled in BIOS or even by choosing performance power plan in OS. (choose minimum processor state 10% in advanced power options for this plan to regain speedstep)

The actual load on the CPU is never a constant and idle does not mean doing nothing. The CPU at "idle" is jumping up and down in multiplier running background tasks and this is the jumping around you are seeing. You have paid good money to see it, it is not a problem.

Offset as I have said applies a value to the whole VID table. Sometimes when setting a negative value idle voltage becomes too low even though the negative value is appropriate for load. In this case adaptive is a benefit since it only applies the offset at load and leaves the idle state alone and at default and the computer will no crash.

The actual voltage you get in CPUz can often be different from what you set or what you think you are going to get when you set offset. This is because LLC will kick in at different levels if you leave it on auto....and the CPU does some complicated calculating not only based on offset values but also taking into account thermal conditions current draw..etc etc. i.e. it takes some executive decisions of its own based on your settings...so exact calculations especially with positive offset values is often not possible. getting to your target voltage is often a bit of trial and error as you will have found.

[VeerK]

I already have EIST and Turbo Speed States enabled. My SSD has set a power management setting where minimum processor frequency is at the full 4800MHz. By default, BIOS has C states on auto. Should I switch it to enable and leave C1,C3,C6,C7 enabled too? What about c state package, C7 vs C7s, and short and long latency for C6 and C7.

Thanks for your help, it was very clear and thorough and I finally understand Adaptive. Basically, at idle and low voltages it will follow the Intel VID table and only at high load will my chosen target voltage kick in via my defined target adaptive voltage and offset. That makes a lot of sense, thank you so much.

Also, is there any benefit to downclocking in addition to dropping voltage? In other words, when I see 4800MHz at .144 volts, is that bad as opposed to letting it drop to 10% via power management at .144 volts?

Also, when setting manual with all c states enabled, CPU Z shows that the voltage is dropping at low load/idle. What is going on in that instance, in terms of voltage, multiplier, and VID table?

[Arne_Saknussemm]

Yes some SSD software sets performance mode in the OS this disables EIST even though enabled in BIOS. You can go into the advanced settings for the power plan and change min processor state from the 100% that is set to 10% and you will recover EIST while keeping the other high performance settings. If I were you I would leave all Cstates enabled there is simply no need to shut them off. Modern processors work even OCd perfectly well with them enabled. I only disable these for benchmarking at very high OCs.

Voltage slowly kills your CPU. the more voltage the shorter is the lifespan of the CPU. How this equation plays out exactly, differs from CPU to CPU and depends on what level of voltage you are talking about. But the less voltage you put through the CPU over time the better. So yes having the voltage drop with multiplier means less voltage passing through the chip in terms of volt/hours as it were. The reaction time of the CPU when it changes voltages is measured in milli or pico or femto (don´t know which) seconds ; up and downclocking is not going to affect your performance in any tangible way. As I say these features are what you are paying for...and work flawlessly even OCing so why not take advantage of them.

The manual voltage voltage drop...has me confused...that is not my experience and I am wondering about your settings...if you are doing something wrong...(though you may not be). Or that C1E now acts even with manual voltage set on this gen of processor where it did not with the former? maybe someone else can confirm or deny that.

[Matt_G]

VeerK,
How are you setting manual VCore?
On my M6E I see two ways to set it that can be construed as manual.

1. Fully Manual Mode - Enabled
I have this enabled and just punch in my voltage in the CPU Core Voltage. I have never seen the voltage drop while the CPU was idling with it setup like this.

2. Fully Manual Mode - Disabled
This is the way you have to have it to do adaptive. But there is also a manual setting in here. With Fully manual mode disabled and CPU Core Voltage set to manual, you can punch in a voltage into the field labeled CPU Core Voltage Override. Is that how you are doing it?
If so, that could be why you are seeing the voltage drop while at idle, though this is a guess on my part.

[VeerK]

I think fully manual mode is exclusive to Extreme boards, I have no such option on my Hero.

As far as what happens I set C states on with manual, according to CPUZ, the same thing that happens when I set Adaptive with C states. I know other people who have seen the exact same results so I am also confused.

I know that voltage shortens cpu lifespan, I was wondering what effect, of any, there is of leaving poweranagement at 100% versus 10%. Both show the exact same voltage drops.

Thanks for the replies.

[Arne_Saknussemm]

Can you not set Ai Overclock Tuner to Manual? this would give you manual control....then set CPU core voltage to manual and you should see no drop in voltage in theory...as far as I know.

If setting 100% and 10% have no different effect it is because that setting is being overridden by something else so no difference.

One last thing...there is a difference between Manual voltage and Offset/Adaptive in that the CPU ups the voltage by 0.1V on detecting AVX instructions (from programs like Prime 95...AIDA...) in Offset and Adaptive.....it does not do this in manual mode.

[Arne_Saknussemm]

Can you not set Ai Overclock Tuner to Manual? this would give you manual control....then set CPU core voltage to manual and you should see no drop in voltage in theory...as far as I know.

If setting 100% and 10% have no different effect it is because that setting is being overridden by something else so no difference.

One last thing...there is a difference between Manual voltage and Offset/Adaptive in that the CPU ups the voltage by 0.1V on detecting AVX instructions (from programs like Prime 95...AIDA...) in Offset and Adaptive.....it does not do this in manual mode.

EDIT: Any joy sorting manual out?

[VeerK]

Well, I can set it to manual, that's how I found my stable 4.8 GHz Voltage before I set it to Adaptive. I just meant that I cannot choose between fully manual mode or not, it just says Manual, Auto, or XMP.

I currently set it to minimum 10% performance and the voltage drops just the same as it would with minimum 100% performance, I don't think it has any negative effect either way.

I know that AVX instructions push Adaptive voltage up by .1v, does that not make Manual with C states more advantageous then? Both Adaptive plus C states and Manual plus C states downclock and downvolt the same, I have no idea why since Haswell Adaptive Mode is supposed to be the best mode to keep the CPU in.

The whole reason I turned to Adaptive is to avoid CPU degradation and keep my rig performing at its best for the next 5 years before I upgrade to a new X99 DDR4 derivative system. Even then, I'd like my CPU to work as a reminder of my first true self-built rig. As such, I'd like your advice since you have a lot of knowledge on voltages. I currently run 4.8GHz at 1.248V stable with overclocked RAM from 1600 to 2133 MHz at 1.65V. Cache ratio is 4.7GHz at 1.2V, VRIN is at 1.8V. I would like to hit 5.0GHz and I think I can with 1.312Vcore, and 2.1 VRIN. I would also run this overclock with Adaptive, but like I said I want to avoid CPU degradation. Do you think I should go for it or live with 4.8GHz?

Other than that, all is well, thank you very much Arne, I learned a lot from you and your explanations.

[Arne_Saknussemm]

Well, that is the key thing...I don't understand why Manual set in AI Overclock Tuner is still downclocking voltage on your system. This should be the difference between manual and adaptive....but given this is the case then sure...setting 10% or 100% will make no difference...

Can't help thinking I'm missing something basic....

Voltages? Well I think you have a very good CPU there right? 4.8 from 1.248 is great and personally I would live there....5.0 from 1.312 is great too though and not a "high" voltage...but the 4.8/1.248 just sounds so sweet!