If you didn't reinstall the motherboard drivers already, go to device manager and disable/re-enable the network adapter.
If that doesn't work, reinstall the drivers.
If all else fails, open elevated command prompt and enter the following functions one at a time, in this order.
netsh int tcp set heuristics disabled
netsh int tcp set global autotuninglevel=disabled
netsh int tcp set global rss=enabled
All I got for you.