I use lenovo two same laptop cable directly connected to the test data, two laptop adapter is gigabit Ethernet cable is also dedicated gigabit Ethernet cable industry, but sometimes speed 100 m and 1 g, sometimes two computers at the beginning of the show is 1 g, copy speed is about 110 m - 120 - m, can I will share the second computer, and then use first computer even second, copies of data and will be the first to the second computer to a Shared folder, copy the half of the time I use 360 uninstall without the application of the computer, I saw the first computer in the unloading here, copy rate suddenly turned into 11 m, looked at the network adapter connection rate was 100 m, I consider is the second computer CPU load affects the speed, so the second computer all applications are closed, but nature is 100 m, so the two network CARDS work mode from full duplex auto-negotiation all into 1 g, disable restart should speak, and I changed back to the two computers in the network card mode automatic negotiation, through the network, but still 100 m bandwidth, Internet and the hardware is ok, consult the circle is a great god... this is, and the adapter to the high-speed data transmission, if the computer system load is too large, the system will automatically reduce the network card rate and working mode? (similar to that of the three-way handshake sliding window), and why I manually full-duplex why not?