How to Install a Desk-Mounted Monitor Arm and Route Its Cables

Quick answer

Start by checking the monitor against the exact arm’s VESA pattern and weight limits. For the listed LX model, those are 75 × 75 mm or 100 × 100 mm and 7–25 lb.

Choose a clamp if the desk edge and underside can accommodate it; consider a grommet mount if there’s a suitable desktop hole or the edge isn’t usable. The listed two-piece clamp fits edges 0.4–2.4 inches thick.

Its grommet mount fits a 0.31–2-inch hole through a surface up to 2.25 inches thick, but check whether that hardware comes with your selected model.

Use the instructions for the exact arm and mount, and secure the base to a surface strong enough to support the equipment before using the arm. Route cables through the designated under-arm path, leaving enough slack for full movement and keeping them clear of pinch points.

Then move the arm through its range to check that it moves smoothly, holds position, and doesn’t snag or pinch the cables.

Step-by-step guide

Check the monitor, desk, and mounting hardware

Before assembly, check the exact LX model’s specifications against your monitor. The listed model supports 75 × 75 mm or 100 × 100 mm VESA patterns and monitors weighing 7–25 lb, so confirm your monitor’s mounting pattern and weight fall within those limits.

Measure the desk where you plan to mount the arm: the listed two-piece clamp fits edges 0.4–2.4 in thick, while the grommet mount fits holes 0.31–2 in wide through surfaces up to 2.25 in thick. Check that the selected SKU includes the grommet hardware, that the desk surface is strong enough, and that you have instructions for both the exact arm and mount; the cited LX guide does not cover mount-specific installation steps.

Sources: Ergotron LX Desk Monitor Arm — mounting options; Ergotron LX Desk Mount Monitor Arm — User’s Guide.

Choose clamp or grommet mounting

Choose the mount that suits your desk layout. A clamp attaches at the desk edge, so use it when the edge and underside can accommodate the clamp within the measurements you checked earlier.

The manufacturer lists its clamp as compatible with freestanding tables and recommends it for panel or cubicle systems.

A grommet mount attaches through a desktop hole. Consider it if a suitable hole is already available or the desk edge is not usable; the manufacturer lists it as compatible with freestanding tables and recommends it for casegoods tables.

Before choosing grommet mounting, confirm the hole fits and the selected arm model includes that hardware.

Sources: Ergotron LX Desk Monitor Arm — mounting options; Ergotron LX Desk Mount Monitor Arm — User’s Guide.

Confirm dimensions and included hardware

Measure the mounting point before installing anything. For the listed LX model, the two-piece clamp fits desk edges 0.4–2.4 inches thick; the grommet mount fits a hole 0.31–2 inches wide through a surface up to 2.25 inches thick.

If you plan to use a grommet mount, measure the hole and desktop thickness rather than assuming an existing opening will fit. Check the exact model or SKU to confirm the grommet hardware is included, since it is not supplied with every variant.

Don’t drill a new hole unless you have confirmed the desk can be modified and have the appropriate instructions. Once the measurements and hardware check out, proceed with the mount-specific instructions for your selected setup.

Sources: Ergotron LX Desk Monitor Arm — mounting options; Ergotron LX Desk Mount Monitor Arm — User’s Guide.

Secure the base to the desk

Use the clamp- or grommet-specific instructions supplied for your exact arm and mounting hardware. The cited LX arm guide does not explain those attachment steps, so don’t substitute its assembly instructions for the mount instructions.

Fasten the chosen mount to a desk surface strong enough to support the arm and monitor, following the manufacturer’s sequence. Before assembling or using the arm, check that the base is securely attached and does not shift; stop if the desk or mount feels unstable and consult the manufacturer’s guidance.

Sources: Ergotron LX Desk Monitor Arm — mounting options; Ergotron LX Desk Mount Monitor Arm — User’s Guide.

Assemble the arm and attach the monitor

With the base securely fastened, follow the assembly and display-attachment instructions supplied for your exact LX arm version. The available LX guide covers arm assembly and monitor attachment, but it applies to a version supplied without a clamp, so use the separate instructions for your selected clamp or grommet mount.

Attach the monitor only after confirming it matches the arm’s VESA pattern and weight limits. Follow the guide’s sequence and use the specified hardware; before moving on, check that the display is attached as instructed and the base remains secure.

If your guide or hardware differs from what you expected, pause and confirm you have instructions for the exact arm and mount rather than improvising.

Sources: Ergotron LX Desk Monitor Arm — mounting options; Ergotron LX Desk Mount Monitor Arm — User’s Guide.

Route cables through the arm

With the monitor attached, place its cables in the arm’s designated under-arm cable route, following the instructions for your exact model. Don’t force cables through gaps or around parts that move.

Leave enough slack for the arm to travel through its full range, and keep cables clear of pinch points. Move the arm through its range while watching the cables; if one pulls tight, catches, or gets pinched, adjust its route or slack before securing the setup for use.

Sources: Ergotron LX Desk Monitor Arm — mounting options; Ergotron LX Desk Mount Monitor Arm — User’s Guide.

Test movement and cable clearance

Move the monitor arm slowly through its full range—raise, lower, extend, and reposition it while watching the cable path. The arm should move smoothly and stay where you place it, without cables pulling tight, snagging, or getting pinched.

If movement catches or a cable binds, stop and reroute it with more slack through the designated path, keeping it clear of moving joints. If the arm moves too easily, feels difficult to reposition, or will not hold its position, use the adjustment instructions for your exact model, then repeat the movement check.

Sources: Ergotron LX Desk Monitor Arm — mounting options; Ergotron LX Desk Mount Monitor Arm — User’s Guide.

Resolve restricted movement or poor position holding

If the arm is difficult to move, moves too easily, or will not stay where you position it, consult the adjustment instructions for your exact model. Make the recommended adjustment, then move the arm through its range again to check whether it moves smoothly and holds its position.

If movement catches or a cable pulls tight, snags, or gets pinched, stop and revisit the cable route. Reposition the cable in the designated path and leave enough slack for the arm’s full range, keeping it clear of pinch points; then repeat the movement check.

The manufacturer’s guide does not specify a universal adjustment procedure, so follow the instructions supplied for your arm rather than guessing at a fix.

Sources: Ergotron LX Desk Monitor Arm — mounting options; Ergotron LX Desk Mount Monitor Arm — User’s Guide.

Next steps

If your monitor matches the arm’s VESA and weight limits and your desk meets the mount’s measurements, choose the clamp or grommet option that suits the available mounting point. If either fit is uncertain, pause and check the specifications and instructions for the exact arm and hardware rather than improvising or assuming a desk hole will work.

Before putting the setup into regular use, move the arm through its full range. If it catches, won’t hold position, or pulls at a cable, revisit the cable slack and route, and use the model’s adjustment instructions when needed.