this issue has been resolved (for me) after i re-installed the Windows 11.  The USB 3.0 is able to give me the write speed 322 MB/s now. Thank you.  Cheers
Hi All,  I would like your expertise to help me on this issue. I did the testing on an alternate desktop to confirm my testing.  System 1 = OptiPlex 5040 with i5-6500 motherboard chipset is Q170 with PCI Express 3.0 and 6x USB 3.0 Ports. System 2 = OEM Desktop with i7-6700 motherboard chipset is Z170 with PCI Express 3.0 and 8x USB 3.0 Ports.both systems' windows are installed with M2 NVME 512 GB harddisk (with Read/ write 3000MB/s) and tested with a SanDisk Extreme Pro USB 3.1 Solid State Flash Drive (with Read/Write 380 MB/s) Test 1 - Copy a big file of 4 Gb. System 1, the USB 3.0 port is able to achieve up to 65   MB/s while System 2, the USB 3.0 port is able to achieve up to 322 MB/s. Test 2 - I bought a dedicated PCI express USB 3.1 card and tested with both PCIe 3.0 x4 and PCIe 3.0 x16 slots  System 1, the USB 3.1 port is able to achieve up to 65   MB/s while System 2, the USB 3.1 port is able to achieve up to 322 MB/s. Now my questions are  Question 1, Why Optiplex 5040 USB 3.0 is able to achieve 65 MB/s instead of 322 MB/s Question 2, Even if i used the PCIe 3.0 x4 slot that may achieve up to 800 MB/s, I am able to achieve 65 MB/s only?Is this Optiplex Motherboard limited the USB speed ?  [IMAGE]  
Optiplex 5040 USB 3.0 slow speed