I have ASRock Fatal1ty 990fx Killer that has the Atheros AR8161 NIC (branded as Killer LAN). I'm direct connecting to a Motorola SurfBoard 6141 with Cat5e cabling. My Windows 7 Professional is set to auto-negotiation and I'm only getting 100Mbps connection. With the same cable plugged into my MacBook Pro from the modem, I achieve a full Gigabit connection. There seems to be many issues regarding this across the web and I'm looking for a solution that will solve my issue.

I've tried both the Killer LAN driver and the driver directly from Qualcomm.

  • Could be a driver problem on Win 7. Aside from the fact that you don't really get 1GBit throughput on any cable system anyway. I have pretty good access and I used the same Cable Modem, and about the max that I have seen on any website is 70 MBit. Thus a 100 MBit connection should do ok.
    – mdpc
    Jan 11, 2015 at 6:45

1 Answer 1


If I understand things correctly:
Both computer network card and cable modem supports 1 Gbps speed.
You have tried with two different drivers for the network card.
When testing the cable on your Mac it achieves a 1 Gbps connection.

It could be that the cable is of poor quality and just barely manages the speed, making it so that the Mac accepts for 1 Gbps speed and the Win7 machine rejects it, falling back on 100 Mbps. Try a diffrent cable to be sure.

A workaround for that should be to change the adapter settings/config and change from auto-negotiation to force "1Gbps Full Duplex" (or whatever they call it). Note, that if the cable really is the problem this may cause issues with lost packets.

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