High CPU Usage When Using MXI-Express with NI-DAQmx and NI MAX Test Panels

Updated Dec 28, 2023

Reported In


  • PXI Remote Control Module


  • Measurement & Automation Explorer (MAX)


  • NI-DAQmx

Issue Details

I have a PXI chassis with several DAQ cards controlled via MXI-Express (MXIe). When I run a LabVIEW VI using NI-DAQmx, I notice my CPU usage on the host PC drastically increase by approximately 20%-40%. I open a NI MAX (NI Measurement & Automation Explorer) test panel to troubleshoot the hardware and I notice that the CPU usage increase again by approximately 20%-40%.  When testing on a PXI with an embedded controller, the CPU on the embedded controller only increases by a small amount. 


Complex MXI-Express configurations may pose a challenge for the host computer BIOS to correctly allocate all the necessary resources. This may cause the system to not enumerate all devices in the system correctly or freeze during the boot process. Given the number of potential computer and MXI-Express configurations, NI cannot completely guarantee compatibility between MXI-Express hardware and your computer. A computer's compatibility with a system may change during each BIOS version/release, which is one of the reasons why MXI-Express compatibility cannot be guaranteed for an individual computer model.
  1. Reset NI MAX Configuration.
    1. If you are using any custom scales or tasks, create a back up of the NI MAX Configuration so they can be imported later.
  2. Try changing PCI/PCIe slots inside the PC.
  3. Verify other cards the CPU usage. If hasn't improved, reinstall NI-DAQmx.
  4. Since the Chassis is operating via a MXI-Express connection to a host PC, install the BIOS Compatibility software.
    1. Check the MXI-Express Products and MXI-Express BIOS Compatibility Software Compatibility and NI MXI-Express BIOS Compatibility Software 18.0 Readme in the installer to ensure the host PC and MXI-Express controller are compatible.
    2. Before creating any changes in the BIOS or installing the BIOS Compatibility software, make a backup or restore point for your PC.
    3. Read the NI MXI-Express BIOS Compatibility Software Readme file in the installer before installing the BIOS Compatibility Software, specifically the Installation Instructions. NI ExpressCard-8360 or NI PCIe-8398 will need to be set to Mode 1 and other devices will need the DIP switch 1 set to the ON position. Do not set any other switch to the ON position.
    4. Install the MXI-Express BIOS Compatibility software.
    5. Ensure the MXI-Express controller is set back to the default setting. For ExpressCard-8360 or NI PCIe-8398 click the Disable button in the NI MXI Configuration program, for other devices set DIP switch 1 back to the OFF position.
  5.  Try changing PCI/PCIe slots inside the PC again

Additional Information

  • All MXI-Express devices, including the ExpressCard-8360, retain their mode settings even after removing the board from the slot or plugging it into a different computer.
  • BIOS enumeration issues can lead to cards not functioning correctly in PXI Chassis as is explained in Understanding MXI-Express Enumeration and Compatibility