Could a bad CAT5 cable result in 10Mbs network speed?

After wrestling with ultra slow internet speeds I finally noticed my Speedtest results were seemingly hard limited at 10Mb/s.

Long story short, I believe I have isolated the problem to the cable or connection of that cable. Is that possible?

I've tried 3 systems at the location of the slow PC (sadly it is my main rig ) and all of them auto-detect at 100Mb/s for a second, disconnect, go back through "Identifying" and re-connect at 10Mb/s Full Duplex. Manually setting 100Mb/s Full Duplex results in no connection.

All 3 systems and the router port are verified to auto-detect at 100Mb/s on other cables.

Odd thing is, I've been running fine for a few months with this (long, 100 foot) cable and getting my normal download/network speeds. It is a recent issue that has come up. Potential that one of my cats damaged the cable slightly or I'm not sure what else could be causing the problem.


Could a bad cable really be at fault? I don't want to order a new one if it doesn't make sense, not to mention routing it through the basement was a PITA the first time. My office is on the other side of the house as the router.

To answer your question. yes. When problems were identified in the past to be cables or electrical interference, I got those exact same results. It would connect for a split second at a higher speed, then disconnect and reconnect at the slower speed. My understanding is that the signal at 100Mbit was so garbled(by whatever.. too long a cable, electrical interference, etc.) that the computer negotiates a slower speed hoping to keep the connection.

If the cable runs near any fluorescent lights, those are big problems. Think about any new electrical equipment you've installed recently that run near where your network cables run. Running cabling by fluorescent lighting is a killer for network signals though.

I'de say yes as well.
Seen some kinked cat5e cables run at 100megs.

Well you can buy a ton of um from newegg or monoprice for cheap..

Thanks guys, I'm going to grab a new cable and a new router (want wireless N now anyway for my Chrome netbook) and sounds like that should fix it.

For what it's worth, I haven't gotten any new electronics or anything like that, but the heat in my basement wasn't working for all winter until recently. Previously it would be ~0F downstairs and now it is ~58F so that could be something.

I have a port on a Gigabyte X58-UD5 board that needs to be very carefully fiddled with to get running at 1gbit, no matter the cable. Usually it runs at 10mbit until its unplugged, plugged back in and wiggled around.

If you have an alternative ethernet port, try switching to that.