Replaced PSU, Network not working

[AP81]

This one has me stumped...

My sister's PC had a faulty PSU (it been shutting down after about 10 to 30 minutes of use and more recently was taking up to 3 minutes to even power on).

I recently replaced it with a decent PSU, however after this, the Internet connection would not work (the limited network connectivity icon would appear in the system tray). I tried my PC and it connects to the Internet fine.

At this point I thought that the onboard network may be faulty, so I stuck a PCI network card in to see if it would work. The same problem occurred with the "limited connectivity" icon.

At this stage my only thought is the motherboard has been damaged by the PSU (maybe undercurrent), but this still seems unlikely to me.

I am downloading Damn Small Linux at the moment to see if the Internet works with that, but apart from that I can't see what else I can do to test it (apart from a fresh windows install).

The Internet was working before I replaced the PSU.

Specs: Cable modem, Socket A motherboard, Windows XP.

Any ideas????

 

[goombawaho]

Reset your TCPIP stack with these commands. Run the first and reboot and see if your problems is fixed. If not, run the second.

netsh int ip reset c:\resetlog.txt


netsh winsock reset catalog

 

[AP81]

Hi goombawaho,

Tried both, but it didn't fix the problem.

Everything else on the motherboard is functioning properly and device manager shows no errors.

I've tried Knoppix on the system and it detects both network devices, however fails to get an IP address using DHCP. So this suggests to me that this is hardware related.

I am still totally confused, mostly because a PCI network card should not have this problem if it is motherboard related.

Well, looks like I'm just going to have to get another motherboard. That is the only thing else I can do...

 

[goombawaho]

Yes - if another operating system is having a problem with the hardware, it would appear to be hardware related. Is there any diagnostic software you can download and perhaps boot from CD that can test your hardware???

The only other possibilities before replacing mobo:
1. verify that cable connection/dhcp works with another "known good" computer.

2. Put the old power supply back in or another one entirely just to see if it's power related.

 

[AP81]

Hi,

I've plugged my PC into the modem and it works just fine. I also tried putting my PSU in the computer and it made no difference.

Thanks for you help. I'm just going to have to bite the bullet and get another motherboard.

Thanks,

Adam

 

[Amos43]

AP81, I know several people who had this problem. In their case, it happened when their computer failed to get a correct IP address from a DHCP server (a.k.a. a wireless/Ethernet router or cable/DSL modem in home networks).

Click start >> run >> "cmd.exe". Type "ipconfig" in the command line. If you see that your IP address does not start with 192.168.0.x, your router/modem may be assigning incorrect addresses to your computer.

To fix this, enter your computer's IP address and the addresses for the DNS/gateway manually. Go to network connections, right click on the connection you're having issues with, and click properties. Select "Internet Protocol (TCP/IP)" and click the Properties button. In the window that appears, select "Use the following addresses" in both sections.

Enter the following information:
IP Address: 192.168.0.x (x between 0 and 255)
Subnet Mask: 255.255.255.0 (set first 3 bytes constant)
Default Gateway: Your routers IP address; commonly, 192.168.0.1 but may differ - look up your router's model number online
Preffered DNS Server: Also router's IP address.

Check out these links:

How to fix unexplained "limited connectivity" notices:

http://www.pchell.com/support/limitedconnectivity.shtml

The official Microsoft article about this:

http://support.microsoft.com/kb/892896

This guy fixed it w/ a 3rd party program:

http://weblogs.asp.net/jld/archive/2004/10/29/249491.aspx

 

[AP81]

Hi Amos,

Thanks for your advice, but if DHCP doesn't work under Linux for both Network devices, then this is beyond a windows problem.

I will give it a try though.

 

[AP81]

Well, I managed to fix the problem. It turned out to be the cable modem.

I unplugged all leads from the modem, let it stand for a minute, then plugged them all back in and voila, all working.

It is strange why my machine managed to connect it this whole time.

 

[goombawaho]

Okay - I've seen that before with cable modems but it completely slipped my mind. It's like the cable modem doesn't like to be hot-swapped to a different NIC. It sometimes does not give out an IP address. And yes, a reboot between swapping computers (unless attached to a router) is always my procedure when I'm visiting someone's house. I wish it would have popped into my head.

It's something about the fact that the MAC address has changed and how the modem reacts to that. Anyone have a technical reason for the modems recalcitrance?

 

[LawnBoy]

Yes. The modem will hand out only one IP, and it will only hand it to the MAC address that was attached to the modem when the modem rebooted.

Why cable co's do MAC aadrress locks, I don't know. The DSL providers in my area don't do MAC locks, even though they're still issueing only 1 IP.


"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes