Actually his motherboard do support gigabit speed on LAN, as per this link,
https://goo.gl/oTrjTW (I've checked for all revision as well)
I would suggest for you to check the ethernet adapter speed (sometimes called as link speed) on your windows machine first. Refer here,
https://goo.gl/Vfq65o. Check whether it is showing as 1.0Gbps or 100Mbps?
From the previous discussion, the most common issues that is bottlenecking the speed is as below:
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1. Cable - Not using cat 5e or above
2. PC - Ethernet adapter driver not up-to-date (go to motherboard driver page and update the LAN driver)
3. PC - Ethernet adapter "speed & duplex" setting not selected correctly
4. PC - Antivirus or firewall setting (please disable temporarily when doing speedtest)
5. Router - Make sure NAT boost setting is enabled (mostly for TP link router)
6. Router - Some router does not support gigabit 10/100/1000Mbps speed on LAN (only support 10/100Mbps)
7. Router - Make sure WAN speed setting is set to 1Gbps or 1000Mbps (by default is auto if I'm not mistaken)
8. Router - Duplex setting is not selected correctly
9. Router - QOS setting (please disable temporarily when doing speedtest)
If all of the common issues above is not related to you, then you might need to connect directly to your modem from your PC via LAN (this will bypass the router). Just setup a PPPOE connection on your windows with your PPPOE username and password. Here, you can perform speedtest to check the 'raw' speed that is coming from the ISP.
I hope this will help.
Hi thanks for correcting me, so does it mean that he needs to flash / update the BIOS / MB if he unable to get the speed ?