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Strange problem about Ethernet speed: recently we bought an i7 core computer running Win7 64 bit with an onboard Gigabit Ethernet controller (Realtek PCIe Gbit Ethernet Family controller).

Connecting this new fast pc directly to our brand new ASUS Gigabit Ethernet router via CAT6 cable(!) shows up the adapter status (see picture attached) only 100mbit, while the router is capable of 1000 mbit. More facts:

  • Connecting an 8 year old IBM notebook with gigabit ethernet to the same cable end shows 1.0 Gbit connection in its adapter status.
  • shows 35 mbit/s down on the new computer
  • shows 78 mbit/s down on the old rusty IBM notebook.
  • We have an 120 mbit down internet connection, which we we truly receive on another pc (also directly connected to the router)

How to get the 1.0 Gbit going in the new pc ?

enter image description here

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Go to Properties >> Configure >> Advanced >> Speed & Duplex and make sure it is set to 1.0 Gbps Full Duplex (or not set to 100.0 Mbps)

Also, Realtek ethernet controllers, that are built into the motherboard do not have a separate processor for handeling TCP/IP traffic. They use the computer's CPU to handle traffic and can get significantly bogged down. I've had this happen, and it was frustrating because download speeds will slow to a crawl after long periods of usage. If that is the case, you might want to invest in a NIC.

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Try forcing the speed of the Realtek to 1000bt in the properties of the connection - it could be an auto-negotiate / auto-duplexing issue. Also, you might want to do the same within the router to see if that does the trick. Also, confirm that you have the latest drivers for your NIC and the latest firmware for your router.

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Router has newest firmware. It is impossible to provide the old notebook with 1.0 Gbit/s if the Router can only provice 100 Mbit. This makes your answer a bit confusing @ BrandonV please clarify. You see, IF the problem is on the ROUTER, and we CHANGE the routers settings, this will cause problems on other computers that currently achieve 1 Gbit/s AND receive 120 of the 120 mbits promised by our internet provider! Thats what makes this problem so strange. – Sam Dec 16 '12 at 21:53

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