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Help with undervolt (i7-8550u, Spectre x360 15t-bl100, ThrottleStop)

Auroric

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New to the undervolting scene, but I recently decided to repaste and undervolt my Spectre x360 15 for better performance, as it often gets hot and turns on the fans even when not under load (browsing the Internet, or even idle). Currently, I'm running at a stable -80mv undervolt on core and cache, and I've repasted with Thermal Grizzly Kryonaut.

Benchmarking with AIDA64 (CPU, FPU, Cache), the laptop will boost to maximum clock for around 3 or 4 seconds (25W pkg power) before dropping to just above its base clock (15W). A few minutes later, it'll start throttling down (pkg power slowly drops to ~13W, clock speeds follow), maintaining temperatures around 65C, despite not showing throttling in AIDA64. ThrottleStop's limit reasons show that it hits red on PL1 and EDP OTHER almost immediately after beginning the stress test.

Putting load on the iGPU along with the CPU makes it throttle even harder, dropping clocks to below 900Mhz after only a few minutes.

Optimally, I'd like the laptop to be able to maintain its boost clock for much longer (especially since it has almost 30 degrees of thermal headroom), and I was wondering if anyone had any suggestions for what I could try. I've attached screenshots of AIDA64 and ThrottleStop (after a long stress test on the CPU) below.
 

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unclewebb

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despite not showing throttling in AIDA64
If AIDA64 is not reporting the throttling problem you are having, why post 3 pictures that show useless data? Nice graphs but what's the point?

Just kidding. :)

Some HP laptops with Intel's low power U series CPUs are locked to 15W and there is nothing you can do about it. Instead of those AIDA graphs, how about a picture of the ThrottleStop TPL window and the FIVR window? Make sure you are using the FIVR - Disable and Lock Turbo Power Limits feature and in the TPL window set the long and short turbo power limits to at least 25W. If you do both of these adjustments and you are still limited to 15W then you are out of luck.

Here is how my Lenovo C930 performs. Exact same 8550U but Lenovo forgot to lock the power limits so it is open season. It runs at full speed until it overheats. Its only limitation is thermal throttling, not power limit throttling.

 

Auroric

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If AIDA64 is not reporting the throttling problem you are having, why post 3 pictures that show useless data? Nice graphs but what's the point?

Just kidding. :)

Some HP laptops with Intel's low power U series CPUs are locked to 15W and there is nothing you can do about it. Instead of those AIDA graphs, how about a picture of the ThrottleStop TPL window and the FIVR window? Make sure you are using the FIVR - Disable and Lock Turbo Power Limits feature and in the TPL window set the long and short turbo power limits to at least 25W. If you do both of these adjustments and you are still limited to 15W then you are out of luck.

Here is how my Lenovo C930 performs. Exact same 8550U but Lenovo forgot to lock the power limits so it is open season. It runs at full speed until it overheats. Its only limitation is thermal throttling, not power limit throttling.

Sorry for the late reply, have been debugging some random BSODs (pretty sure one, or both, of my RAM sticks are failing). With the changes you recommended, the laptop still seems to drop to 15W under load. I've included the screenshots of FIVR and TPL you asked for, just in case I'm missing something. It definitely stays at 25W for a lot longer though (around 20 seconds, until it reaches around 74C and begins to throttle).
 

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unclewebb

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seems to drop to 15W under load.
HP has locked your laptop to 15W long term. There is no simple solution to get around this limitation. ThrottleStop cannot be used to get beyond this limit.
 

Auroric

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HP has locked your laptop to 15W long term. There is no simple solution to get around this limitation. ThrottleStop cannot be used to get beyond this limit.
Well that sorta sucks :(. Guess I'll take this opportunity to pivot over to working on something else. Do you have any recommendations for an on-battery profile with regards to FIVR settings and TPLs? Of course, I'd like the laptop to still be able to hit its base clock (or better), but also to reduce the power consumption so it lasts longer when I don't need the performance, like browsing the web or watching a video. I've noticed that, when idle, the CPU boosts up to its boost clock speed and I feel like the extra power consumption there isn't necessary.
 

unclewebb

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Here is an interesting comparison.


Huge difference in CPU speed and huge difference in VID voltage but no difference in power consumption. Intel CPUs are extremely efficient. The speed they run at when lightly loaded makes very little difference. When a CPU core has nothing to do, it enters the low power C7 state. In this state, it is disconnected from the internal clock and it is disconnected from the voltage rail so it is sitting there doing nothing at 0 MHz and 0 volts. You cannot improve upon this. Changing the speed and voltage of what the active cores are doing makes very little difference.

If a core has something to do, holding it to a slow speed wastes more power than it saves. Look at the above example. A 100% increase in voltage allows the CPU to run 200% faster. That is a good trade off. A fast CPU is an efficient CPU. It gets its work done quickly and this allows it to spend more time in the low power C7 state where power consumption is minimal. You can try adjusting things but you might not see any significant difference in power consumption.

ThrottleStop 9.2 gives you access to the traditional Windows Power Saver profile.


Will it save you any power? Maybe, maybe not. Will it make your CPU run slow and sluggish when lightly loaded? Definitely. Microsoft removed access to this profile for a reason. Perhaps it was not saving as much power as its name implied.
 

borygo77

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Try this one :) I'm running this for sometime now and it makes wonder speaking about performance :) It's elitebook x360 830 G6 with 8565u proc... If your bios isn't locked you might find those settings helpful ;)
 

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