I would guess so, but i want to make sure.

Is the bracket of a graphics card grounded to the ground-plane of that card?

The metal bracket is the thing with the DVI, HDMI, DisplayPort etc. connections.

enter image description here


After measuring with a multimeter, i suspect that brackets (of most graphics cards) are grounded to the graphics card's ground-plane.

I measured 0 ohm between the traces around the motherboard screw holes and the bracket of a (old) 75W graphics card. (All power from the PCIe x16 slot. No power cable needed. So, graphics card's ground-plane == motherboard's ground-plane.) The motherboard was outside the case, on a wooden table.

On some newer graphics card, a screw (which fastens the bracket to the board) is clearly visible on the back side, suggesting direct contact between the bracket and the graphics card's ground. (This construction also counteracts sagging. A little bit.)

enter image description here

Although a graphics card's bracket probably is grounded to the card's ground, it might be possible there is some sort of non-conducting coating on the bracket. Then you'll have to touch the screw holes around the DVI port, to reach equipotential.

  • 2
    \$\begingroup\$ Of course. When you plugged that cars into M/B and screwed it gets connected to the earth. So it should be grounded. \$\endgroup\$ – Rohat Kılıç Jan 7 '17 at 11:34
  • \$\begingroup\$ @RohatKılıç Yes, then the bracket is grounded, thru the ATX case, to earth. But is the bracket itself (out of the box, before installing) electronically connected to the GND pins of the power-jack on that same graphics card? \$\endgroup\$ – Marty Jan 7 '17 at 11:35
  • \$\begingroup\$ Usually the holes that the bracket screws into the card through are plated and connect to ground, much like the holes on a motherboard. \$\endgroup\$ – Tom Carpenter Jan 7 '17 at 11:41
  • 6
    \$\begingroup\$ Measure it with a meter. \$\endgroup\$ – Andy aka Jan 7 '17 at 11:51
  • \$\begingroup\$ The screws for the DVI connector is what grounds the bracket when unconnected. \$\endgroup\$ – winny Jan 7 '17 at 12:09

The bracket is certainly grounded to the case by mechanical contact when installed.

However, it is up to the card designer as to whether the bracket is directly bonded to the card's power supply ground. I would actually expect that there would be some isolation via some combination of resistor/capacitor/diode in order to avoid creating ground loops through the motherboard. But this would still provide some degree of protection from ESD if you handle the card by its bracket when not installed.

  • \$\begingroup\$ Yes, when installed in an ATX case, the bracket/faceplate of any graphics card is directly bonded to that case. But i was wondering whether the bracket/faceplate is bonded to the GND of the graphics card. Because, if it is, then touching the bracket/faceplate with your fingers (while being grounded to earth yourself) would bring the graphics card at earth potential. When the motherboard (on which that card should be installed) is also at earth potential: no ESD, while installing the card. \$\endgroup\$ – Marty Jan 8 '17 at 18:01
  • \$\begingroup\$ If the bracket/faceplate isn't bonded to the graphics card's GND, then touching the bracket won't equalize the charges. So, there could be a potential difference between the graphics card and the motherboard. \$\endgroup\$ – Marty Jan 8 '17 at 18:04
  • \$\begingroup\$ All I'm saying is that there will generally be a connection, but not necessarily a direct metallic connection. A connection through a resistor or an inductor still eliminates potential differences (static charges) while limiting the current when needed. \$\endgroup\$ – Dave Tweed Jan 9 '17 at 1:02
  • \$\begingroup\$ Thanks! That's good news. So, probably, touching the bracket does the trick. (On most graphics cards.) \$\endgroup\$ – Marty Jan 9 '17 at 12:43

In theory, the faceplate of an electronic device with "hot pluggable" cables should not be connected to signal ground directly. The idea behind is that the path of current from any ElectroStatic Discharge (ESD) will go into metal housing (which is normally connected via metal chassis to Earth ground) first, and will not cross board signals. Even if the board ground is made of flooded copper layer and has low impedance, kV-level voltages from ESD can create substantial voltage "bouncing" across the signal ground, exposing signals between internal chips to dangerous overvoltage.

  • \$\begingroup\$ Interesting, because i thought that the shield of, for example, an USB-jack (also hot-pluggable) should be connected directly to the GND of that jack. That GND ís the ground of the motherboard. \$\endgroup\$ – Marty Jan 8 '17 at 18:33
  • \$\begingroup\$ @Marty, here is an answer about how to connect USB shield, electronics.stackexchange.com/questions/269244/… \$\endgroup\$ – Ale..chenski Jan 8 '17 at 19:03
  • \$\begingroup\$ Okay. So, regarding to an USB-jack, the shield wire connects to the metal shield of the jack. That metal shield connects to the ATX-case. No direct path from metal shield to the GND of the jack. \$\endgroup\$ – Marty Jan 8 '17 at 20:02

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