Windows 7 / Getting Started

Understanding USB Limitations

If you installed the USB device's software correctly and you are using the most up-to-date version of the driver, you still might have problems because of USB's physical limitations. Limitations that can cause problems include:

  • Insufficient power Many USB devices receive power from the USB port. Connecting too many unpowered devices to a USB hub can result in a power shortage, which can cause a USB device to not respond properly. This is particularly common when using an unpowered external USB hub. To quickly determine whether a problem is power related, disconnect other USB devices and connect each USB device directly to the computer one by one. If devices work when connected separately but fail when connected simultaneously, the problem is probably power related. Decrease the number of devices or add a powered USB hub.
  • Excessive length USB devices can be no more than 5 meters (16 feet) away from the USB hub to which they are connected. Although USB devices will never ship with cable longer than 5 meters (16 feet), some users connect USB extenders to allow longer distances. Depending on the quality of the cable and possible sources of interference, you might experience problems with shorter distances. To determine whether length is the source of problems, remove any USB extenders and connect the USB device directly to the computer.
  • Too many devices USB can support up to a maximum of 127 devices connected to a single USB host controller, which is more than enough for the vast majority of client computer scenarios. You can have a maximum of seven layers of USB hubs connected to the computer's USB host controller, and no more than five external hubs.
  • Insufficient bandwidth Most USB devices are designed to work within USB bandwidth limitations. However, video cameras in particular might need more bandwidth than USB is capable of providing. If you receive a "Bandwidth Exceeded" message, first try disconnecting other USB devices. If the message continues to appear, attempt to reduce the bandwidth used by the device by lowering the resolution of the camera. For best results with a video camera, connect it to an IEEE 1394 (also known as Firewire or iLink) port.

Note If you see the message, "Hi-speed USB device is plugged into non-hi-speed USB hub," the USB device is USB 2.0, but the USB port is an earlier version. The device will probably work, but it will work slowly. You can improve performance by adding a USB 2.0 port to the computer.

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In this tutorial:

  1. Troubleshooting Hardware, Driver, and Disk Issues
  2. Windows 7 Improvements for Hardware and Driver Troubleshooting
  3. Windows Troubleshooting Platform
  4. Built-in Troubleshooting Packs
  5. Windows Troubleshooting Platform Components
  6. Creating Custom Troubleshooting Packs
  7. Running Troubleshooting Packs Remotely
  8. Windows 7 Reliability Monitor
  9. Windows 7 Resource Monitor
  10. Windows Memory Diagnostics
  11. Disk Failure Diagnostics
  12. Self-Healing NTFS
  13. Improved Driver Reliability
  14. Improved Error Reporting
  15. The Process of Troubleshooting Hardware Issues
  16. How to Troubleshoot Problems That Prevent Windows from Starting
  17. How to Troubleshoot Problems Installing New Hardware
  18. How to Troubleshoot Problems with Existing Hardware
  19. How to Troubleshoot Unpredictable Symptoms
  20. How to Diagnose Hardware Problems
  21. How to Use Device Manager to Identify Failed Devices
  22. How to Check the Physical Setup of Your Computer
  23. How to Check the Configuration of Your Hardware
  24. How to Verify That System Firmware and Peripheral Firmware Are Up to Date
  25. How to Test Your Hardware by Running Diagnostic Tools
  26. How to Simplify Your Hardware Configuration
  27. How to Diagnose Disk-Related Problems
  28. How to Use Built-In Diagnostics
  29. How to Use Reliability Monitor
  30. How to Use Event Viewer
  31. How to Use Data Collector Sets
  32. How to Use Windows Memory Diagnostics
  33. Memory Failures
  34. How Windows Automatically Detects Memory Problems
  35. How to Schedule Windows Memory Diagnostics
  36. How to Start Windows Memory Diagnostics When Windows Is Installed
  37. How to Start Windows Memory Diagnostics from the Windows DVD
  38. How to Configure Windows Memory Diagnostics
  39. How to Troubleshoot Disk Problems
  40. How to Prepare for Disk Failures
  41. How to Use ChkDsk
  42. ChkDsk Examples
  43. ChkDsk Syntax
  44. How to Use the Graphical ChkDsk Interface
  45. How to Determine Whether ChkDsk Is Scheduled to Run
  46. ChkDsk Process on NTFS Volumes
  47. How to Use the Disk Cleanup Wizard
  48. How to Disable Nonvolatile Caching
  49. How to Troubleshoot Driver Problems
  50. How to Find Updated Drivers
  51. How to Roll Back Drivers in Windows 7
  52. How to Use Driver Verifier
  53. How to Use the File Signature Verification
  54. How to Use Device Manager to View and Change Resource Usage
  55. How to Use Windows 7 System Restore
  56. How to Troubleshoot USB Problems
  57. How to Solve USB Driver and Hardware Problems
  58. Understanding USB Limitations
  59. How to Identify USB Problems Using Performance Monitor
  60. How to Examine USB Hubs
  61. How to Troubleshoot Bluetooth Problems
  62. Troubleshooting Tools
  63. DiskView
  64. Handle
  65. Process Monitor