Why can my application not utilise all the CPU before having CPU-related performance issues?

[kombob]

I have a Dell Precision 7550 laptop with an Intel i7 10850H processor and 16GB RAM. I am running Windows 10, and have all the drivers, firmware and BIOS up to date. In the BIOS, I have 'Intel Speed Step', 'Intel Speed Shift', and 'Intel Turbo Boost' settings enabled - basically all default options in the BIOS.

In the 'Dell Power Manager' application, I have the mode set to 'High Performance'. When I click on the Battery icon on task bar, I dragged the slider all the way from 'Best battery life' to 'Best performance'.

In the Application I am running (Ableton Live 11, running Pianoteq plugin with 128ms buffer speed), I am experiencing audio drop outs despite Task Manager showing the clock speed to be less than the 'stated' maximum of 5.1GHz. I say this is the 'stated' because in actual fact I can never reach above 4.3GHz from CPU-hungry Applications (like Ableton Live 11 running Pianoteq at 128ms buffer).

While the processor does reach 4.3GHz in the above scenario, it's not staying there, and audio dropouts seem to sort-of 'take priority' over the CPU reaching 4.3GHz - I would prefer:

• the application to squeeze every drop of clock speed before malfunctioning.
• the application to be able to utilise the full 5.1GHz clock speed rather than the 4.3GHz limit I am experiencing

I have set Ableton to launch on 'high' priority by default, but it hasn't helped.

I have seen the clock speed reach 4.8GHz shortly after reboot (i.e. Windows starting up). So is it the case that 5.1GHz max clock speed is just for OS-related stuff, and user applications are only allowed up to 4.3GHz?

How can I get my CPU to increase its clock speed to get the most out of it before I experience audio dropouts?

Please do not tell me to increase buffer size. In order, I want to: (a) ensure I'm getting most out of my CPU, (b) increase buffer size if still experiencing problems. This post is about (a).

Thank you.

[n_scott_pearson]

The answer is simple: They've given you a crappy cooling subsystem and processor performance has to be throttled to stay within the cooling envelope that this crappy cooling subsystem can deliver.

Another common trick to make their battery subsystems look better is to limit processor performance based upon power consumption.

Ok, off my soapbox and my despise for all things Dell.

Achieving and sustaining the Max Turbo Boost frequencies is dependent upon many factors, including the thermal head room available (read first paragraph above) and the number of cores that are currently active. For more information, consult these pages:

• What is Intel Turbo Boost Technology and How Does it Work?
• Why Am I Not Getting the Intel Turbo Boost Frequency?
• My Intel Core Processor Does Not Reach the Maximum Turbo Boost Frequency
• Frequently Asked Questions for Intel Turbo Boost Technology
• Frequently Asked Questions About Temperature for Intel Processors

Hope this helps,

...S

[kombob]

As to why the CPU does not reach 4.3GHz before audio drop outs:

The cooling capability is not the cause of what I describe.

• This is a premium mobile workstation with large cooling fans and heat sink assembly.
• The temperatures of the CPU during what I describe are not high, and the cooling system is consequently not heavily active.
• If temperatures do rise in response to 100% CPU usage, the cooling system is capable of maintaining around 4.3GHz indefinitely under 100% CPU usage in stress tests - but again, this isn't the applicable to the situation I describe.

The battery is not the cause either.

• This happens when operating on AC power.
• I'm not reaching anything like 100% CPU usage during the scenario described, and the GPU (an NVIDIA Quaddro 2000) is not engaged at all. There is plenty of wattage left for additional CPU performance.

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As to why applications (including stress tests, performance tests) are only able to hold the CPU at 4.3GHz and not the 5.1GHz max turbo boost frequency:

This may well be an imposed limitation of the mobile CPU and/or mobile workstation for power/thermal reasons. Which leads to my question...

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What I'm asking is:

1. Is it normal that the 'Maximum Turbo Boost Frequency' of 5.1GHz is not practically attainable for user applications, but seemingly available to the OS for short bursts?
2. I have seen the clock speed stay around 4.8GHz for a around 25 seconds during start-up, even though CPU usage was only around 10%. This would be perfect for my situation, as clock speed is most important for low-latency, pro-audio plugins. How can I achieve this?
3. Even if the realistically achievable clock speed for user-applications is 4.3GHz, how can I allow the user applications to reach this before having audio drop outs?

[n_scott_pearson]

Have you looked for Turbo Boost settings in the laptop's BIOS? While it is not common to expose these (because tuned to cooling and battery capabilities) in laptops, who knows?

In regards to your questions,

1. Yes, perfectly normal. The highest Turbo Boost settings (I am saying settings, rather than capability, because laptop vendors can limit this through those Turbo Boost settings that I mentioned above) is only attainable when a single core is active, the thermal headroom is available and a bunch of other criteria. Read the specs I pointed you to above.
2. Again, the time window is part of the Turbo Boost settings. You can only change this if the settings are exposed in BIOS Setup (again, not common in laptops).
3. How do you know that the audio dropouts are actually because of the processor? What are you basing it on? Regardless, you should be discussing the performance issues with Dell, not us.

Hope this helps,

...S