Excel Performance Problems

Fix Excel Not Using CPU Cores Across NUMA Sockets

Nimra Malik Sep 28, 2026 869 views

Question details

Excel restricts CPU usage to 16 cores on a dual-socket workstation and fails when processing tasks that require cores across both NUMA sockets.

How to Fix Excel Not Using CPU Cores Across NUMA Sockets

Product: Microsoft Excel
Device & OS: not provided
Scenario: Running multi-threaded, heavy calculation tasks on a dual-socket workstation that require high CPU core utilization across the entire system.
Observed behavior: Excel utilizes up to 16 cores but fails to bridge NUMA sockets, frequently resulting in calculation failures or unexpected OEM licensing authentication errors.

Before you start

Ensure your Windows operating system and Microsoft Excel are fully updated, and verify that your dual-socket workstation's BIOS settings are correctly configured for NUMA architecture.

Solution 1Recommended

Diagnose NUMA and Licensing Errors with a Sanitized Test File

Create a sanitized version of your workbook to isolate whether the limitation is caused by Excel's configuration, hardware NUMA boundaries, or OEM licensing authentication.

Because dual-socket workstations introduce complex NUMA (Non-Uniform Memory Access) boundaries, Excel may struggle to allocate threads effectively. Furthermore, OEM licenses (like telephone-activated Dell licenses) may trigger authentication timeouts during heavy multi-threaded loads.

Create a copy of the workbook

Duplicate your heavy calculation workbook and remove all sensitive or proprietary internal data to create a sanitized test file.

Document exact error messages

Force the calculation that crosses the NUMA sockets and take screenshots of any specific error messages, especially those related to OEM licensing or authentication failures.

Upload and share for support analysis

Upload the sanitized test file to a cloud service like OneDrive or Google Drive, generate a shareable link, and provide it to Microsoft Support alongside your error screenshots for deep diagnostic analysis.

Diagnose NUMA and Licensing Errors with a Sanitized Test File

Solution 2

Manually Configure Excel's Multi-threaded Calculation

Force Excel to use all available processors instead of relying on automatic thread allocation, which may fail to bridge dual-socket NUMA boundaries.

Free Microsoft Office alternative

Try WPS Office for High-Performance Spreadsheet Processing

If Microsoft Excel is bottlenecked by NUMA socket limitations or recurring Dell OEM licensing authentication errors on your workstation, WPS Office provides a lightweight, highly compatible alternative for handling large datasets without complex licensing hurdles.

1. Download the software: Visit the official WPS Office website and download the free installer for Windows.
2. Install on your workstation: Run the installer and follow the on-screen prompts to set up the lightweight office suite.
3. Open your files directly: Launch WPS Spreadsheet and open your .xlsx files to resume your data analysis without OEM licensing interruptions.

Fully compatible with Microsoft Excel formats (.xlsx, .xls, .csv).Lightweight architecture optimized for smooth performance on modern multi-core hardware.Free from Microsoft OEM telephone activation and simultaneous authentication bottlenecks.Familiar tabbed user interface, ensuring zero learning curve for existing Excel users.

microsoft office alternative - wps office

Frequently Asked Questions

Why does Excel fail to cross NUMA nodes on a dual-socket PC?

Excel's multi-threading engine can sometimes struggle to schedule processing threads efficiently across Non-Uniform Memory Access (NUMA) boundaries. This often leads it to maximize thread limits on a single physical socket (e.g., 16 cores) rather than utilizing the full capacity of the entire system.

Can a high volume of simultaneous authentications cause Excel to crash?

Yes, certain OEM licenses, such as telephone-activated licenses, may experience authentication timeouts or failures when a heavy, multi-threaded calculation triggers multiple simultaneous validation checks across system processes.

How do I share a workbook securely for performance troubleshooting?

Remove all proprietary and internal data, replace sensitive text with dummy data, and upload the sanitized file to a secure cloud service like OneDrive. Generate a restricted sharing link to provide to support technicians so they can replicate the performance issue safely.

Excel & Data Problems