Do I need to check Sync MMIO for Throttlestop to use adjusted PL1, PL2, and Turbo Time Limit values?

[dbookbinder]

I've been trying to create a low-power/low-heat setting for my i7-1355U HP laptop cpu, which appears to be largely locked down.

If I modify the PL1, PL2, and Time values in TPL, do I need to check Sync MMIO in order for them to be enforced, or will they be enforced anyway, as long as Throttlestop is running? Also, what effect does checking Clamp have? Does it more strictly enforce these values or do something else?

Also, are there any other values I can alter to prevent heat-related throttling of the power cores (especially one of them)? Adjusting the TPL Speed Shift Max value, which someone on reddit suggested, seems to have no effect.

Thanks!

 

[unclewebb]

The MSR and MMIO are two separate sets of turbo power limits. I prefer to check the MMIO Lock box near the top right of the TPL window. This tells the CPU not to use this secondary set of turbo power limits. With the MMIO power limits locked out, you can adjust the MSR power limits to control the CPU. When MMIO Lock is checked, you do not need to check Sync MMIO.

Clamp

This tells the CPU to slow down as much as necessary during any power limit throttling. When Clamp is not checked, the CPU should only slow down to the base frequency. Check both Clamp boxes if you want your MSR power limit values strictly enforced.

which someone on reddit suggested, seems to have no effect.

Do not believe everything you read on reddit.

When cores are equally loaded, if one core runs much hotter than the others, this is usually a sign of poor cooling. It might be a heatsink that is not perfectly flat, or it could be bent or perhaps it was not screwed down evenly. It could also be a poor application of the thermal paste. One hot core can trigger thermal throttling prematurely and reduce the overall performance of the entire CPU. Whether the CPU thermal throttles or you adjust the power limits and force the CPU to power limit throttle does not make much difference. Throttling is throttling. There is no way to adjust the power limits for a single core.

 

[dbookbinder]

Thanks for your reply. A follow-up question: When the cores are equally loaded, as when I'm running Cinebench or Prime95 without specifying I run them single-threaded, the core temps are close, with the two power cores running a little hotter. When I use a single-threaded app, one of the two power cores overheats, almost always core #1. Is there anything I can do to mitigate that, given that I can't adjust power limits for a single core? Or is this essentially a non-problem, given the limits of the laptop's cooling architecture?

 

[unclewebb]

Not much you can do. The typical cooling systems used by laptop manufacturers are no match for the heat generated by Intel's latest mobile CPUs, especially when they are allowed to run at full speed and full power.

this essentially a non-problem

It is definitely a problem but there is no simple solution. The market demands thin and light laptops. A thin laptop has no room for a heatsink that is big enough to properly cool the CPU. Avoid buying thin laptops if you plan to play games or do any serious work on it.

 

[dbookbinder]

Live and learn. My next computer will be a desktop.