I have 2 w7pro boxes on a home workgroup gigabit lan running on Asus P8Z77 motherboards with Realtec PCIe GBE NIC's. One box has an i7 2700 processor and one an i7 3770. Both connect to a Vigor 2800 router through a Netgear gigabit smart switch. Both boxes use fixed ip addresses on a 192.168.3.x subnet. Both have a similar collection of application programs.
As far as I can tell both NIC's are set up identically although the driver versions are different they both report that the best driver is installed.
Both boxes report broadband download speeds of around 11-12 Mb/s which is correct for my connection. While the 2700 box uploads at 0.7 to 0.8Mb/s (again correct) the 3770 only manages between 0.01 and 0.02 Mb/s.
I have of course bypassed the switch and house cabling by connecting the box directly to the router, but it makes no difference. There is nothing in the router or switch configs to indicate why the upload speed is so low. Pings to google.com from a cmd window are identical on both boxes at 37ms.
There is nothing that I can see to explain the poor upload speed on the 3770 box. Can anyone give me some pointers where I should be looking next?
It seems clear that it is a box issue, but I can't find the problem.