# MS Surface Pro 3 - BSOD on Disable Turbo setting



## maekel (Feb 4, 2021)

Hello guys,
I've been happily using TS for a while on my MS Surface Pro 3 (i5-4300u 1.9ghz/2.5ghz boost Win8.1 64bit).
I run it with -85mv undervolting across the board and it seems pretty stable.
My only concern is that I get instant BSOD if I turn "Disable Turbo" setting on the primary screen.
There seems to be no way properly restricting turbo mode with TS on MS.SPRO3. I tried Intel XTU utility it handles things well, so there seems to be some sort of issue with TS driver.
With TS I have to play around restricting "Set Multiplier" down to 11-18 depending on the setting profile. Interestingly enough, Set Multiplier of 19 releases the limitation completely, i.e. CPU turbo's up to 2.5 under load.

Please advice if there's anything I can do to make "Disable Turbo" feature safe of BSOD. I would also appreciate for a recommendation around settings.







Appreciate your help and big thanks for a very useful CPU undervolting utility.


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## unclewebb (Feb 4, 2021)

maekel said:


> I run it with -85mv undervolting across the board and it seems pretty stable.


If checking the Disable Turbo box causes a BSOD then your undervolt is not stable. My computer does not crash when I check or clear that box. Set the voltages back to their default values and then try toggling the Disable Turbo feature. Make sure the FIVR monitoring table shows +0.0000 in the Offset column. You should never see a BSOD. An undervolt is only stable if it is stable at any CPU speed or at any load; light load or full load.

A 4th Gen U is already a low power CPU. When you use the Offset Voltage feature, it will lower the voltage along the entire voltage curve. You might be 100% stable when you reduce the voltage by -85 mV at full load or at full speed but this can cause instability when your CPU is lightly loaded or idle or if the CPU is allowed to go down to its minimum speed. This is very common with 4th Gen mobile CPUs, especially the low power U series.



maekel said:


> Set Multiplier of 19 releases the limitation


If you want Set Multiplier to work correctly, go into the FIVR window and set the Non Turbo Ratio to 0. You will also need to switch to the Windows High Performance power plan. When you are using the Windows Balanced power plan, you have created a situation where Windows is writing one value to the CPU control register and you have ThrottleStop writing a different value to the same register. This is never good.

If you are going to use the Windows Balanced power plan then do not check Set Multiplier.

The 4300U supports a maximum multiplier of 29 when 1 core is active. If you are using Set Multiplier, set that to 29T for maximum CPU speed. This CPU should use a 26 multiplier when 2 cores are active. Run a 1 Thread TS Bench test with ThrottleStop set up properly and see what multiplier it reports while the CPU is loaded.


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## maekel (Feb 4, 2021)

unclewebb said:


> If checking the Disable Turbo box causes a BSOD then your undervolt is not stable. My computer does not crash when I check or clear that box. Set the voltages back to their default values and then try toggling the Disable Turbo feature. Make sure the FIVR monitoring table shows +0.0000 in the Offset column. You should never see a BSOD. An undervolt is only stable if it is stable at any CPU speed or at any load; light load or full load.
> 
> A 4th Gen U is already a low power CPU. When you use the Offset Voltage feature, it will lower the voltage along the entire voltage curve. You might be 100% stable when you reduce the voltage by -85 mV at full load or at full speed but this can cause instability when your CPU is lightly loaded or idle or if the CPU is allowed to go down to its minimum speed. This is very common with 4th Gen mobile CPUs, especially the low power U series.
> 
> ...


Thank you for you guidance, it really helped. First time ever disable turbo with no BSOD. Looks like running on Balanced Win profile was causing the issue.
I reset voltages and turned settings back to default, but now facing new challenge. Single thread never spin the Turbo mode, until I set/release Set multiplier to 25.







Now pressed and released Set Multiplier while running TS Bench.



What am I doing wrong here? I also included TPL setting screen




Appreciate your time explaining the details, I read every manual of TS I found, but still a bit unclear of the settings.

What would be your recommendations on using or not Set Multiplier? The only reason I wanted to use one is to force the slowest profile to keep CPU at 800Mhz.
And I think I'd need to find the way for TS to co-exist with Windows power plans as Windows can control the rest of laptop power consumption, which TS doesn't (i.e. PCI Express, Cooling and etc).


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## unclewebb (Feb 4, 2021)

maekel said:


> First time ever disable turbo with no BSOD.


It was definitely your undervolt causing the problem. -85 mV was too much. Maybe try -50 mV instead.

If you are using the High Performance power plan then Set Multiplier needs to be checked. Do not check and uncheck it. Leave it checked all of the time so the CPU control register can be monitored and adjusted if needed.

Why is Set Multiplier still set to 25? Increase that to the maximum value which should be 29T. In the FIVR window the default 1 Core Active value is 29. Why is that set to 26? Is there a reason you are trying to run your CPU slower than its default speed? Intel CPUs can run reliably at high temperatures. Your CPU is set to start thermal throttling at 90°C which is already 10°C lower than the 100°C Intel recommended value. No worries.


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## maekel (Feb 4, 2021)

Ha.. found it. Had to lower PowerSaver C0% to make single thread kick in the Turbo mode..



unclewebb said:


> It was definitely your undervolt causing the problem. -85 mV was too much. Maybe try -50 mV instead.
> 
> If you are using the High Performance power plan then Set Multiplier needs to be checked. Do not check and uncheck it. Leave it checked all of the time so the CPU control register can be monitored and adjusted if needed.
> 
> Why is Set Multiplier still set to 25? Increase that to the maximum value which should be 29T. In the FIVR window the default 1 Core Active value is 29. Why is that set to 26? Is there a reason you are trying to run your CPU slower than its default speed? Intel CPUs can run reliably at high temperatures. Your CPU is set to start thermal throttling at 90°C which is already 10°C lower than the 100°C Intel recommended value. No worries.


Yes, there's a reason, I'd like to hold my horses a bit as SPRO3 cooling isn't all that great and even with all the geeky radiators glued to the back of it, I'd like to avoid running into 80C. Had already repaired all the power parts on the motherboard ones (maybe I should just buy a newer device...).
But before I throttle it down to 70C, I'd like to make sure I understand what's the optimal performance setup .
With Set Multiplier at 29T, I constantly run at 2.7-2.9Ghz, which doesn't seem right for a ultrabook. Shouldn't CPU be going down to 800Mhz when idle to keep laptop cool for spike of the workload later?
SPRO3 really do not run well over 80C and throttle CPU heavily back over 82 I believe.

And no, it is not the undervolting that was causing BSOD, but using Windows balanced power plan with disabled Turbo in it in parallel with TS trying to disable Turbo. I made couple more tests.
This is what kills it.


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## unclewebb (Feb 4, 2021)

Here is a good comparison. Same CPU, same computer. Picture on the right shows the CPU running at 3 times the speed and the VID voltage is more than 3 times higher.






You would think that there would be a huge difference in power consumption and heat. Guess what? There is no difference at all.

When an Intel CPU is idle, cores automatically enter the low power C7 state. In this state, the core is disconnected from the internal clock and it is disconnected from the voltage rail so it is spending the majority of time sitting idle at 0 MHz and 0 volts. When trying to reduce power consumption, concentrate on how much time the core is spending in C7 and ignore the speed of the rest of the CPU. A fast idle speed allows this CPU to process all of the Windows background tasks while only needing to spend 0.3% of the time in the C0 state. What speed the CPU is running at when in C0 is unimportant because it is hardly spending anytime at this speed.

The screenshots posted so far are showing that you probably have too much stuff running in the background. Lots of people install stuff and do not look at how it impacts idle activity. With a 2 core CPU, you have to be extra aware of everything you install.

If you get a BSOD at default voltage then that looks like a Windows bug. Maybe Windows is not happy that ThrottleStop is trying to control the CPU. It is OK not to be happy but it is not OK to crash with a BSOD.

Your temperature problem is because of power consumption not speed of the CPU. Instead of trying to control the CPU speed, why not lower the turbo power limits? The CPU will power limit throttle so it does not get too hot. Match power consumption to what your heatsink is designed to handle.


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