hello every one I am new to this site.:cool:

I am running windows xp sp2.
my inbuilt ethernet card is Realtek RTL8139/810x
when I connect ethernet wire to modem and cpu, both are unable to read it.
so, I have to use usb cable to connect to network.
I have replaced modem twice
& I also checked ethernet wire
& I had also checked device manager, it says device is working properly
& I also updated driver
but problem persist

1st question: Do you have a link light at both ends?

No

Then before you go any further, try a known good cable.

You could have a cross-over cable and neither machine supports an auto-midx port and that cable could possibly work somewhwere else that does support an auto-MIDX port.

Look at at TELEPPHONE cable by holding the ends in the same orientation. contacts down and hold by the cable.

I'm saying look at a telephone cable, because the colors are easy to see. Pin 2 goes to pin 5, pin 3 goes to pin 4. Pins 1 and 6 are unused. There may be 6 gold contacts (6P6C) or there may be 4, (6P,4C) so just pay attention to the wires. Telephone cables are cross-over cables. They typically have places for 6 contacts. In rare instances I've seen only 2 (6P,2C).

Heck, you can just look at the center two pins which will be green and red. In one connector green will be on the left and in the other connector green will be on the right.

Check your Ethernet cables (straight-thru) the same way. In this case pin 1 connects to 1, 2 to 2, 3 to 3 etc. It will be much harder because all of the conductors will have a lot of white. Only pins 1,2,3 and 6 are required for 10/100 Ethernet to work.

This link should shows difference between (straight) and (crossover) cable

Ethernet Cable: Color Coding Standard (http://www.incentre.net/incentre/frame/ethernet.html)

Your cable should be -- T-568B Straight-Through Ethernet Cable -- Looking at the colors on wires

Hope this helps --- Please rate my answer

I've used the T-568A coding scheme on installations as well as the T-568B. The trick is to make sure that both ends of the RJ45 connector as identical on a straight through.

Did the modem (I'm assuming cable modem and not DSL) come with an ethernet cable as part of the install? If you are using that cable, chances are that it's OK.

If you changed out the modem twice, and the cable, chances are that the ethernet port on your motherboard may be out. The device manager may be reporting a working device, however the physical pins may be the problem on the port.

See if the pins on the board are still straight and not being obstructed.

Thany you guys I will try it

Did you mean you are unable to connect your modem with you cpu?