Windows 10 normally uses all processor cores that are available to it. You do not need to open System Configuration and select the highest number under “Number of processors” to unlock hidden performance. That boot option is primarily useful for testing configurations with fewer processors.
Check how many cores Windows sees
- Press Ctrl + Shift + Esc to open Task Manager.
- Select Performance.
- Choose CPU.
- Look for the Cores and Logical processors values.
Logical processors can be higher than physical cores because technologies such as simultaneous multithreading allow a core to expose more than one logical processor.
Leave the msconfig processor box unchecked
Open msconfig > Boot > Advanced options only if you are diagnosing an existing boot configuration. With Number of processors unchecked, Windows is not being told to limit itself to a manually selected count.
Checking the box and selecting the maximum does not make Windows use cores it was otherwise ignoring. Old “speed up Windows” guides often misinterpret this setting.
If Task Manager shows fewer cores than expected
Confirm the exact CPU model and its specifications. Then check firmware settings and the computer/motherboard manufacturer’s documentation. A virtual machine can also be configured with fewer virtual processors than the host CPU physically contains.
Do not change BIOS CPU settings casually
Firmware can expose processor, virtualization, overclocking, or core-related controls. Change them only when you understand the specific setting and have model-specific documentation. Resetting firmware defaults may be more appropriate when an unexplained configuration change caused the problem.
More cores do not make every task proportionally faster
Software must be designed to use parallel processing effectively. A lightly threaded application can remain limited by one or a few cores even when Windows recognizes the entire CPU.
Windows 10 support context
For this guidance, remember that Windows 10’s standard free-support period ended October 14, 2025; post 59503 should be maintained with that lifecycle in mind. If performance is the concern and the hardware supports Windows 11, moving to a supported operating system is preferable to applying unsupported boot “optimization” tweaks.
Matt Jacobs has been working as an IT consultant for small businesses since receiving his Master’s degree in 2003. While he still does some consulting work, his primary focus now is on creating technology support content for SupportYourTech.com.
His work can be found on many websites and focuses on topics such as Microsoft Office, Apple devices, Android devices, Photoshop, and more.