bizarre problem with network cable

I'm experiencing a really bizarre issue with a new 25 ft. cable I purchased. It works with one machine, but not the other (well, it works but it is really, really slow).
I have both machines side by side. Cable #1 is 12 ft long, Cable #2 is 25 ft. Both cables work with my Athlon machine (I get the exact same speed to the internet -- 1.8 Mbs).
The short cable, when used with my K6-2/350 machine, gives me the 1.8 Mbs speed that the Athlon machine gets. The long cable, used with the K6-2/350 machine, gives me 500 *bytes* per second throughput.
The Athlon machine has ethernet built into the motherboard. The K6-2/350 box just got a new Netgear FA-311 card installed...
Now, why would the long cable work with the first machine, and not the second? I have a hard time believing it is a problem with the second machine, because the shorter cable works just fine. And besides, the cable is only 25 feet long -- it's not like I'm dealing with a 200 ft cable or anything..
Any help would be greatly appreciated!

1. RE: bizarre problem with network cable
lbyard Oct-11-01 05:20 PM
In response to message 0

http://duxcw.com/faq/network/slownet.htm. (Obviously) that's long enough to see machine-specific problems if the cable is defective. It's almost always a cable problem. Larry

2. RE: bizarre problem with network cable
nebeker Oct-11-01 05:27 PM
In response to message 1

After spending a while on hold, I finally got through to Netgear's technical support. Their recommendation was to change the network card's speed from "autosensing" (which was putting it in 100Mb mode) to 10Mb mode.
As soon as the change was made, everything started working fine -- and I was getting the same 1.8Mbs throughput as the other machine...
thanks for your comments.

3. RE: bizarre problem with network cable
lbyard Oct-12-01 08:09 PM
In response to message 2

That's fine if you are communicating directly with a 10 MHz device, such as a cable MODEM and it may produce good Internet results; however, it is not a satisfactory fix in my opinion if you are communicating with a 100 MHz device, such as another computer, hub, or switch. If you plan to share files between the two computers the connection will be noticeably slower than one that is working correctly. Larry