By default, most systems have some bandwidth reserved for nothing. You can change
* Open gpedit.msc from the run box in the start menu.
* Navigate to: Local Computer Policy > Computer configuration > Administrative templates > Network > QoS Packet Scheduler
* Open Limit Reservable Bandwidth
* Check the enabled box and change the Bandwidth Limit to 0%.
Depending on your system, this might need a restart to start working.
Happy Surfing !!