Is a there a means to lower Quadro M4000/P4000 radiated emissions from its display ports (HDMI mode)?

Graphics / Linux Linux
1

Our embedded system runs Yocto with Nvidia driver 384.69 and is driving all four display ports. 2 ports are used as DP to drive built in monitors and the remaining two are in HDMI mode to service external monitors . Currently through xorg.conf “ConnectedMonitor” option we set all four ports are connect and active always, regardless of whether external display devices are plugged in. This was chosen to prevent dynamically arranging the GUI when external monitors are connected or removed.

This configuration was passing radiated emissions testing at the EMC test house when we were using M4000. However, since M4000 is EOL, we replaced it with P4000 and now the radiated emissions is much higher and not passing the EMC standard. Our EE suspects that the P4000 has sharper clock edges and generating more noise. Are there SW configurations that we can set to the GPU to affect the electrical characteristics of the DPs? Thanks in advance.

P.S. We know P4000 is also EOL, but that will another day’s issue.

2

I don’t think there’s an option to control what the display engines are outputting on the wire.
Does it fail EMC test while the external monitors were connected? If not, is this depending on the ConnectedMonitor option? Otherwise, shielded dummy plugs might be an option.

3

generix, thanks for the reply. We will find out whether having a monitor/video sink helps or not the next time in the test house. Unfortunately, the test requires us to plug in a HDMI cable (with no monitor) into the port, so a dummy plug is not allowed. The ConnectedMonitor option keeps the port active thus generating noise. We can modify the software to disable the port when no monitor is detected, this remove the emission as expected. However this create complexity in the embedded software.