Desktop kills internet even when no network connected, on boot

Hi,
a very odd one, that has me baffled.

My Asus M4A78-vm AMD 955 4ghz 2010 built PC has a legacy issue that when it is booted it kills my LAN at home and mostly shows up when trying to get onto the internet. It does this at power up (pre-windows 7 pro 64bit). It also does this when no network cable is plugged in.

I have tried disabling the Logitech wireless keyboard in case this was killing my router wireless (etech adsl 2/2+ router) but no fix, and anyway wireless not used on desktop and only for my phone.
I tried disabling wireless on router in case it was a hardware electronic signal issue from the desktop but no fix.

I re-installed windows 7 and no fix, but its PRE-windows start-up.

It can be fixed if the router is rebooted, ok so your now thinking router is the issue, but I have a second desktop and a laptop that both present no problems like this day in day out. It’s only the desktop that causes the failure.

I am at the stage where I am going to strip parts out of the desktop reboot and see which bit fixes the issue, maybe its something spiking the router? long shot?

Any ideas or tests please do share.

Andrew
Ex Network consultant (this is embarrassingly hard to fix and my wife is not impressed at my skills!!!)

Halt the booting of the desktop by going into BIOS. If this kills the internet, then the issue might be power related. Perhaps a voltage drop as the desktop starts up.

UsernameIssues said:

Halt the booting of the desktop by going into BIOS. If this kills the internet, then the issue might be power related. Perhaps a voltage drop as the desktop starts up.

Hi, forgot to say I thought it might be this and did that test and yes its pre-windows launch. I connected the base unit to a different ring main from the loft one (where my computer is) and still got the issue, so should not be a voltage issue.

Andrew

It might not be worth the time or the cost to find the exact cause. It might cost less time and money to replace the router and/or the computer's power supply.

If you can borrow a router from a friend and/or neighbor - you could test to see if it is taken down by your computer.

Or, set the desktop to halt the boot if a keyboard is missing (or some other boot fail, like taking the HDD out of the boot order), then take the desktop to a neighbor's home and power it up. If it takes down your internet from that far away, then call the local press - you've go a story to tell.

If it takes down their internet (perhaps they have the same router with the same susceptibility).

I can only guess that your router is being taken down by some freakishly strong and/or freakishly specific EMI. If that is the case, then it is probably best to buy a different router.

If you want to chase the cause down a bit more - you can disconnect the computer's power supply from everything, load it with a power supply tester or resistors and then power it up to see if it alone takes the router down. But even that simulation might not cause the power supply to do exactly what it does while in the computer.

Hi,

I set the bois to has no boot device, and problem still there so EMI looking very likely. I had an idea (bit crazy but may work) to shield the router from the desk top (either tin foil or sheet metal) I let you know my results.

Andy

Shielding the router is hard to do if other LAN cables are still attached... not to mention the power cable. Find a good ground to tie your shield to if you are going to try that.