[SOLVED] Causes of Desktop EMFI

[Thetypest57]

I have a custom build desktop and another person has two hosts. My host and one of the other hosts rely on wi-fi while the third is wired. When my desktop is on, the internet speeds of the other hosts drop from 140mb down to 5mb down, while my wi-fi speed remains constant at 140mb. The first thing I did was to deactivate my wireless NIC to see if the signal improved, but it did not. Not until my desktop is fully off do the wired and wireless speeds of the other machines improve.

I had initially believed that this was signal interference from a bunch of packets bombarding our router (mixed wired/wireless) with packets. However, after having deactivating the wireless NIC in the Windows Device Manager without an improvement for the other hosts, I now believe that my desktop is causing severe EMFI attenuating both the wireless signal and wired. Although I could be mistaken, I'd appreciate your help understanding what in my custom rig is causing this kind of interference for the other systems.

My system is a 2014 build:

-6th Gen i7 i74790K
-ASRock Z97 Extreme 4
-EVGA Supernova 750 G2
-Qualcomm Atheros AR938x
-Asus Xonar DSX
-NVIDIA GeForce GTX 660
-LG HL-DT-ST-BD-RE WH16NS40
-Drives:

1. SanDisk SDSSDHP128G
2. ST1000DM003 - ICH1
3. Hitachi HDE721010SLA330
4. ST3160811AS

 

[SamirD]

I haven't seen systems interfere with other things since the days of our 486 monster build that when we powered on would actually cut out half of the radio stations on a radio 8 feet away. Still that doesn't mean it can't happen today.

One sure fire way to test your theory is to simply wrap the offending system in aluminum foil and see if it makes a difference. If so, you're on the right track.

While interference with wifi would be easy, interfering with wired would require noise on the ground and affect the system in general. This can point to an actual wiring problem with the outlet.

 

[kanewolf]

Is their"wireless" signal supplied by a powerline network adapter? Your power supply could be the noise that is causing problems.

 

[Thetypest57]

I haven't seen systems interfere with other things since the days of our 486 monster build that when we powered on would actually cut out half of the radio stations on a radio 8 feet away. Still that doesn't mean it can't happen today.

One sure fire way to test your theory is to simply wrap the offending system in aluminum foil and see if it makes a difference. If so, you're on the right track.

While interference with wifi would be easy, interfering with wired would require noise on the ground and affect the system in general. This can point to an actual wiring problem with the outlet.

How do you suggest that I do that? Wrap everything except the NIC rubber ducks?

 

[Thetypest57]

Is their"wireless" signal supplied by a powerline network adapter? Your power supply could be the noise that is causing problems.

Yes, but not one of the two suffering speed degradation.

 

[bill001g]

How do you suggest that I do that? Wrap everything except the NIC rubber ducks?

If you have the wifi radio off and no ethernet connection that only leaves interference via the power cable or through the air. You could take a extension cord and plug the pc into a different outlet. Running the computer on a UPS running on battery would really be the only way to eliminate interference being sent into the power

The best test is likely to just move your pc some distance away from the one it is interfering with. The drop in radio signal is exponential compared to distance so it should not take much.

Unless you are using one of those glass computer cases your machine is already wrapped in steel. Since the power supply is bolted to the case and it connects to the ground wire in your house you should already have a Faraday cage. Generally wifi cards that people place internal to a desktop machine without external antenna do not work at all because of the metal case so you would think it would keep interference inside.

If you were to cover your computer in foil it likely would only be short term because it would overheat. You would more likely use aluminum window screen for long term but it should not really be needed.