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[toulouse]

....is this weird.

Hiya guys (and gals),

I just wondered if anyone would like to comment on the following....

                            ADSL --------------------+
                                                              |
                                                              V

My setup consists of Computer 1 ---> Netgear DG834 (v3)

                                                              |
                                                              v

                                                          Netgear GS608 (v2)
                                                             |   |    |    |
                              Computer 2 ---------+   |    |    |
                              Computer 3 -------------+   |    |
                              Computer 4 -----------------+   |
                                  ...                                       |
                              Computer n ---------------------+


I'm with PlusNet and always synch at 8128Kbps (so far, anyway). I also run RouterStats (v3.1) and my Rx noise is generally in the region of 6-8dB. Computer 1 is running Windows XP Home, 2, 3, 4 are running various flavours of Linux (Fedora Core 6 & 7).

Normally Computer 1 is on from very early in the a.m. and the Linux machines get switched on as and when required. Now, I'm sorry if it seems that I'm waffling, but here's the thing.........

.......when Computer 3 is powered up, the RouterStats trace, which as I said is normally between 6-8dB, always drops to somewhere between 0-2dB, specifically during the boot sequence of Computer 3. It then returns to the normal range of 6-8dB. My understanding is that RouterStats is monitoring the ADSL signal quality / line noise, so why should powering up another machine affect that trace ?


Any thoughts anyone ?

P.S. apologies for the poor diagram

[b4dger]

Not so weird... 
It looks like that PC is causing lots of 'noise'.  Can be coming from numerous components - screen, power supply, etc.
Once it's up and running things return to normal - whether a component is failing is hard to say...

[toulouse]

Yes, I suppose a failing component could always be a possibility. But the machine was only put together in the last 12 months using all new components.

[mr_chris]

To me it seems pretty cut and dried - it's *something* in that PC causing the interference. Does the phone line run near to it? Perhaps enabling spread spectrum in the BIOS might help.

Have you tried powering it on without the display and seeing if that makes it better or not? Unfortunately it's just a logical case of fault-finding. Does it also happen whilst playing games e.g. a lot of traffic on the graphics / memory bus, and CPU usage. Or it could be during periods of massive hard drive usage.

It might even be the power supply, which is probably one of the easiest components to swap between two systems to check out if that's the issue or not.

Unfortunately you're going to have to do a bit of digging to find the cause of the issue.

Good luck

[toulouse]

In the words of my hero Mr H Simpson of Springfield, USA, 'Doh'.

I must have been having a SENIOR / BLOND / TOTAL KLUTZ moment when I posted yesterday. I completely forgot to mention that Comps 2, 3 and 4 all share the same monitor, keyboard and mouse via a Sitecom 4 port KVM switch. I will try connecting the 'problem' computer to a spare port on that box and see what happens. Is it likely to be the KVM box ? I know that this type of equipment, i.e. low cost, is often supplied with cheap power supplies.

What I  am having trouble understanding is why the "problem" only occurs during boot up of this particular machine. Surely, if it was a failed / failing component it would cause the problem as long as the machine is powered up and network connected, or am I wrong about this.

Note for Mr Chris

1) the phone line runs almost 2 metres away from the machine, but I do use some lengthy network cables
2) will check out the 'spread spectrum' option that you mentioned
3) I'm not a game player, so the graphics activity is unlikely I think.

and finally, thanks for the good luck. I'd better roll up my sleeves, I guess.

[Ezzer]

Check the monitor lead from the new pc, does it have a cylindrical attatchment on it anywhere (your other monitor leads would typicaly have these. If not then swap it with another monitor lead and see if the effect has moved from one pc to another, if yes then:

 http://www.maplin.co.uk/Search.aspx?criteria=ferrite&source=15&SD=Y

See the clip on ferrites, try giving one of these a go on the cable

[mr_chris]

Surely, if it was a failed / failing component it would cause the problem as long as the machine is powered up and network connected, or am I wrong about this.

Not necessarily. Computers often work a lot harder during bootup than they do whilst they're booted. It's not necessarily a failed / failing component, just one that's badly shielded or causing RFI for some reason.

When you're booting up, there's a LOT of hard drive activity. While the PC's on - there's often very little.

When you're booting up, power consumption is often very high whilst the OS boots and before it loads ACPI and CPU drivers to reduce power usage during normal operation.

Basically, to find this fault swapping around power supplies, hard drive cables, graphics cards, monitor leads etc, is the only way to try and isolate what's causing the interference. It's really difficult and even quite daunting, but hopefully I've given you a couple of potential starting points!

Good luck, again!