In one of my previous posts, we had reported intermittent video/monitor "blanking". Almost as if a monitor was disconnected and re-connected. This would happen only to certain users. the main commonality (so far) is that all of these users either plugged their phone into the front of the PC (and phone was on PC or near it) or they had a police radio (Motorola 800 MHz) nearby--like on desk or worn while they were on the PC.
Dell never responded/replied to the previous posts, so I am putting this out there (and in general hardware) to see if this is a common issue.
Please post here if you are having similar interference/monitor blanking issues.
Interference, indicated by a buzzing sound, static or service cutout, is caused when the computer and other devices operating on the same frequencies. Radio interference with PCs can work both ways: the computer can interfere with other devices, and other devices can interfere with the PC. Nailing down the exact cause of interference can be time consuming or inconclusive.
Disconnect any unnecessary components and peripherals from the computer to eliminate as many interference-causing parts as possible. For example, disconnect unused speakers, network adapters, printers and input devices; anything with a current could be the cause. If the interference dissipates, use the process of elimination to determine the guilty part.
Connect the computer and the interference-suffering device to different electrical sockets. Bad wiring in the wall could be causing the interference and not the device itself. If the devices interfering with each other are connected to the same outlet, try moving one to a different outlet.
Create as much distance as possible between the PC and other interference-causing or receiving devices. Computer-related interference may affect only devices that are close to each other.
Tie up long cable slack or replace long cables with shorter cables. Cables and wires are more prone to radiation interference than actual circuit boards. Minimizing cable space decreases interference.
Install EMI ferrite coils on cables and wires. EMI ferrite coils act as a choke point for radio frequency interference and can stop devices from interfering with each other. The computer's power supply is the likely culprit; however devices like the keyboard and monitor have large unshielded areas prone to interference.
Use computer speakers that feature an electrical ground and have shielded wires. If the speakers aren't grounded and shielded, they can be prone to picking up any nearby transmission.
Change the router's Wi-Fi broadcast channel. Wi-Fi operates at a much higher frequency than other radio devices, but may interfere with things like baby monitors and cordless phones.
Turn on any nearby microwaves and check the PC for interference. Microwaves are notorious for causing interference. Either move the PC away from the microwave or avoid using the microwave while using the PC.
step 1- only minimal components are installed--mouse, keyboard
step 2- our electric is fine-- plus its all on ups backup (this is happening in multiple locations/buildings--only on the 5040 sff))
step 3- distance is the same as all the other models we have had---so fat the 5040 sff is a commonality
step4- all cables are standard length-- no extensions on any device
Step5- have not installed these...will see if I can get my hands on some
step 6- speakers are same as before --DELL undermount
Step 7 not on wifi--still Ethernet
Step 8- no nearby microwaves.
again-- this was never an issue with the previous models. (790/7010) just on the 5040's so far