Intel Speed Shift technology also known as HWP (Hardware p-state) or Hardware Controlled Performance delivers quicker responsiveness with short duration performance shifts, by allowing the processor to more quickly select its best operating frequency and voltage for optimal performance and power efficiency.

For performance, efficiency and power consumption reasons, modern processors are constantly changing clock frequency and voltage based on the workload. In order to receive performance hints (p-states) and adjust performance according to the operating system, application or user needs, processors prior to Skylake model are relying on the operating system. The problem with this approach is the level of latency that is added to the performance adjustment process, which slightly reduces overall performance as a result. One can certainly avoid this problem altogether by selecting for instance, maximum performance. However, this will can reduce the battery life for portable devices, increase power consumption, and thermal output.

Starting with CPU codename Skylake, the problem with performance control adjustment was addressed with Speed Shift (Hardware Controlled Performance) also known as Intel HWP (Hardware p-states). With Speed Shift enabled, CPU takes over the responsibility of frequency control, which will be done on a hardware level by the CPU itself, this’ll allow much faster p-state transitions and can drastically reduce latency during the process of p-state selection.

PreviousNext

That being said, even with Intel Speed Shift support enabled CPU will not be able to jump from low to high frequency level and back instantly, due to various factors such as voltage, heat, data coherency etc. So if you do want/need the absolute best out of your CPU, you'll still have to set performance to maximum manually. This'll disregard the scaling part of the process and will be effectively the same as setting multiplier to maximum.

If Speed Shift is enabled by default on the BIOS or OS kernel level it cannot be turned off by the application. However, if it's not enabled by the OS or the BIOS and still supported by the CPU itself, the application can manually enable Speed Shift feature which will be disabled again on system restart or deep sleep.

While Speed Shift is relying on the CPU hardware, it still takes performance hints (performance settings) which includes minimum, maximum and desired performance limits from the operating system or the user in order to maintain specific level of system responsiveness.

On the main application form you can observe Performance control indicator which will show two states Speed Shift or Legacy. If Speed Shift performance control is active, by clicking on SpeedShift link you'll be taken to Speed Shift control tab on Advanced CPU settings form.

The fact that Performance control indicator is set to Speed Shift will show that performance requirements need to be adjusted using the Speed Shift tab on Advanced CPU settings form, while Legacy setting indicates that performance can still be controlled on the main form by modifying Turbo boost and Frequency scaling sliders.

Intel Speed Shift feature support multiple levels of control; Core, Package and PECI.

• PECI: represents an individual controller to control p-state hints. If supported, PECI level control has the highest priority and will override both Core and Package level controls, however you won’t find PECI controller on most system (PECI Support: No), so you probably don’t have to worry about it.
• Core: Performance hints are applied to each individual core. Core level control (most common) has the highest priority after PECI and will override Package level settings.
• Package: Performance hints are set at the package level. And last Package level control has the lowest priority of the three.

On most systems your Setting for selection will be set to Cores unless your CPU is supporting Speed Shift Package level control as well. In either case selecting Cores is a recommended way since Cores settings takes precedence over the Package level control.

Slider controls described below can be used to specify performance hints for Speed Shift related performance settings:

• Minimum allowed performance: Will specify minimum allowed clock frequency for the CPU. (Minimum possible clock ratio supported by the CPU can be found on CPU information tab)
• Maximum Allowed performance: Will specify maximum clock frequency that CPU can utilize
• Desired performance: Will specify desired performance level. When set to zero, hardware authomatically determines the performance target. When set to a non-zero value specifies an explicit performance request hint to the hardware.
• Energy performance preference: Energy efficiency preference to influence the rate of performance increase /decrease and the result of the hardware's energy efficiency and performance optimizations. Range of values from 0 (performance preference) to 255 (energy efficiency preference).

The settings described above will tell the processor which performance level you prefer to maintain. For example by setting minimum performance to value 9 (0.9 GHz) and maximum performance to value 20 (2.0 GHz) you are telling the processor that you would like to keep your CPU clock frequencies between 0.9 GHz and 2.0 GHz, depending on the workload. For instance if your max CPU frequency is 4.3 GHz, your clock speed won't go above 2.0 GHz. This will make a positive impact on the battery life because of the low power consumption, considering you are using a portable device.

As it was already mentioned on Advanced CPU Settings section, once all the Speed Shift modifications are applied, the application will begin to monitor all of the available settings listed on the Settings panel (not only those you just modified). This means that if any other application or system attempts to modify your settings, Quick CPU will detect the change and will make an attempt to revert this change back to the state when you last Applied your changes. It’s important to note that you need to keep the application running (can be in the system tray or task bar) in order for it to monitor your settings

PreviousNext

[ Click to enlarge ]

One way to apply your SpeedShift setting on application start is to create a custom profile with preferred Speed Shift modifications and apply this profile on application start. You can read more about this here: How To Apply Custom Profile Settings On Application Start

These controls indicates whether PECI based Speed Shift control is supported and if it’s currently active.

1. If PECI support is set to No you system is not supporting PECI controller (other PECI indicators will also be set to 'No')
2. If PECI support is set to Yes your system is supporting PECI controller, in which case you can monitor in real time PECI override events for performance hints.

The following PECI indicators are available:

• Min PECI override: Yes/No
• Max PECI override: Yes/No
• EPP PECI override: Yes/No

The indicators above can be used to identify if PECI controller is currently performing Speed Shift hint override in which case PECI defined settings are taking priority over OS or User defined settings. OS/User can reset those settings when override event is over (set to No)