Problem in time of continuous acquisition PCI NI 6534 on Windows 10

Hi,

I'm using the NI 6534 (PCI interface) with the driver NI-DAQmx 19.0 to acquire continuous data using C++ program on Windows 10, the acquisition time of every block is calculated in 2.56 seconds, but when this value is monitoring over time I observe critical variations around this time (2.56 sec) as attached in the graphic Block_time_Windows10_PCI_NI_6534_2_56sec.jpg.

When I changed the NI 6534 by the NI 6537B (PCIe interface) with the same driver and S.O., in this case, the acquisition time is more stable as is shown in the graphic Block_time_Windows_10_PCIe_NI_6537B_2_56sec.png. Are there any solution for the NI 6534 to work stably in the time on Windows 10? I try to raise the privileges of the software to work in real-time, even modify the interrupt that manages the NI 6534 but I get the same, but I get the same behavior.

I would appreciate any response,

Thanks