Hide Cables in Fishtank PC Cases (Grommet Routing)
To hide cables in a fishtank PC case, route them through existing case openings fitted with grommets sized for the opening and panel thickness. Keep wires clear of fans, vents, sharp edges, and panels that move. Follow the case and cable makers’ instructions, secure bundles without crushing them, and check the build before powering on.
A fishtank case puts more of your build on display, so a loose fan lead or thick power cable can draw the eye from the components you chose. That can be frustrating after investing in a clean-looking PC. The neatest route is not always the safest one, though: cables still need room to bend, stay clear of fans, and remain accessible for service.
In my work with system layouts, I start with the case’s intended cable paths rather than forcing wires behind the visible side. A grommet can protect a cable where it passes through metal, but it cannot fix a poor route or an opening that does not fit. The guide below covers how to plan, fit, route, and check cables in a glass-heavy PC case.
Planning — intent and governing principle
Planning means tracing each cable from its source to its connector before tying anything down. Use the case’s existing pass-throughs where possible, and protect cables wherever they cross a metal edge. Follow the instructions for the case, power supply, cables, and grommets; no universal PC-case rule sets one correct grommet size or routing clearance.
Start by identifying which cables need to be visible and which can sit behind the motherboard tray. Common examples include the 24-pin motherboard cable, GPU power leads, CPU power cable, fan wires, and front-panel I/O leads. Plan each run separately before combining cables into a bundle.
Look for factory cutouts, rubber grommets, tie-down points, and channels behind the tray. Then check for obstacles: fan blades, radiator faces, vent openings, removable filters, and the path of any panel you need to reinstall. A cable route that looks clear with the case open may become pinched when a panel goes back on.
A simple route map helps:
- Trace the cable from its source to the connector it must reach.
- Choose the shortest practical route through existing openings.
- Check that the connector can pass through the opening without force.
- Leave enough slack to unplug or reposition the part later.
- Mark any point where a cable crosses metal or approaches a fan.
Do not drill or enlarge an opening in tempered glass. Glass panels can shatter if drilled or altered. Use factory metal pass-throughs or a pass-through approved by the case maker instead. If the planned route cannot avoid glass, reconsider the route rather than trying to create a new hole.
Access and clearances — verified specifications and entities
A safe route protects cable insulation, respects the cable’s bend limit, and leaves moving or ventilated parts unobstructed. There is no single bend-radius value that suits every PSU, USB, fan, or display cable. Check the cable maker’s stated limit, and do not force a tighter bend to make the wiring disappear.
Choose a grommet that fits
A grommet is a ring or lining that protects a cable where it passes through an opening. Match it to both the opening diameter and the case panel’s thickness, using the grommet maker’s specifications. It should seat fully and resist pulling through with gentle cable movement. Do not force a grommet into an opening outside its stated size range.
If the case has a factory grommet, inspect it before use. Replace it if it is loose, cracked, or missing. A bare punched edge or a visible burr can damage cable insulation. Every cable crossing a metal opening needs a properly seated grommet or other suitable edge protection.
When choosing a polymer grommet, look for published material and flammability information where available. UL 94 V-0 is an example of a material flammability rating. That rating alone does not certify the finished PC or prove that a particular grommet is right for your case.
Check bends, fans, and airflow
Cables need to curve without kinking or pressing hard against connectors. Look up the cable maker’s minimum bend radius if one is listed. If you cannot confirm it, avoid sharp folds and leave a smooth curve rather than pulling the wire tight around a corner.
Keep cables outside the full area swept by fan blades. A 5 mm gap is a practical no-contact target during assembly, not a code-mandated clearance. Check again after fitting panels and filters, since those parts may shift a cable or change the space around a fan.
Do not cover a vent, radiator face, or fan inlet with a cable bundle. Fishtank cases vary in layout, so there is no universal airflow or CFM figure that applies to all of them. Preserve the case’s designed intake and exhaust paths.
| Route or component | What to check | Practical pass condition |
|---|---|---|
| Metal pass-through | Grommet size and panel thickness | Grommet seats fully; no exposed sharp edge |
| Cable bend | Cable maker’s bend limit | Cable curves without a forced kink |
| Fan area | Blade path with panels installed | Cable stays outside the swept area; 5 mm is a practical target |
| Vent or radiator | Intake and exhaust openings | Bundle does not cover the airflow path |
| Panel edge | Panel movement and fit | No cable is pinched when the panel is closed |
Execution — progressive implementation
Execution is the careful installation of the planned route. Fit the grommet first, then pass cables through without twisting, straining connectors, or crushing insulation. Secure the finished runs to case tie points, and leave enough slack for service without allowing cables to drift into fans or block airflow.
Route and secure the cables
Power down and open the case. Follow the case and component makers’ instructions for access. Do not open the power supply itself. If you are changing internal connections, disconnect power and follow the relevant equipment instructions.
Fit and inspect the grommet. Confirm its opening and panel-thickness range match the case. Seat it fully, then check that no sharp metal remains exposed around the cable path.
Pass cables through gently. Guide connectors through without twisting the wires or pulling on terminals. If a connector will not pass through, do not force it; choose another suitable route or follow the cable or case maker’s guidance.
Set the visible-side runs first. Route GPU, motherboard, and fan wiring through the closest suitable opening. Keep runs tidy, but do not pull cables so tight that they load a connector or create a sharp bend.
Bundle only where useful. Use reusable ties or hook-and-loop straps at case tie points. Tighten them only enough to stop the bundle moving. A strap that flattens or crushes insulation is too tight.
Keep service slack. Leave enough cable to unplug a fan, remove a component, or open a panel without pulling on the connector. Tuck excess length behind the tray only if it does not press on a panel or block another part.
Recheck clearances. Look at each fan, vent, and panel edge again. A cable that is secure in one position can shift when a panel, filter, or radiator is installed.
Two common build scenarios
These examples describe typical layouts, not tests of a particular case model. They show how the same checks apply to different cable problems.
GPU power lead crossing the display side: A builder sees the cable run across the glass-side view. I would first look for a nearby factory opening between the GPU and the rear cable chamber. If it fits the connector and grommet, route through it, keep the cable’s curve within its stated limit, and secure the slack behind the tray. Do not pull the lead tight just to make it vanish.
Fan wire near a radiator: A fan lead hangs near a blade or lies across a vent path. Route it along the frame to a tie point, then guide it through a protected opening if needed. Check the full blade path and radiator face after reinstalling the filter and panel. Adhesive or tape alone is not a safe fix if the wire could drift into a fan, block ventilation, or be pinched.
The key trade-off is between a clean view and access. A cable hidden so tightly that it cannot be unplugged without strain is not a good finished route. Keep the visible side orderly while leaving useful slack behind the tray.
Verification — critical edge case, heading blueprint, and exclusions
Verification means checking the completed route with the case assembled, not just while the side is open. Confirm that grommets remain seated, no wire is pinched, fans have clear space, and vents are open. Recheck the wiring after moving a component, changing a panel, or replacing a cable.
Test before closing the build
Before powering on, inspect each pass-through and the cable along its full length. Look for scraped insulation, tight bends, loose grommets, and connector strain. Confirm that no cable can fall into a fan’s blade path when the case is moved or a filter is removed.
Refit panels and filters slowly. If a panel resists closing, stop and find the cause rather than pressing harder. A cable may be trapped between the panel and case frame. Once assembled, check that fans spin freely and that cable bundles do not cover vents or radiator faces.
NEC 110.3(B) concerns listed equipment where applicable and reinforces following equipment instructions; it does not set a universal PC-case grommet size or clearance. NEC, IRC, and IBC do not provide one general grommet specification for routing inside a PC case. Use the instructions for the actual case and parts.
Frequently asked questions
Can I route cables through any opening in a PC case?
No. Use an opening that suits the connector and route, and protect every metal edge with a correctly fitted grommet or equivalent edge protection. Do not use a bare punched edge, and do not force a grommet into an opening outside its specified size range.
How do I choose the right grommet size?
Check the grommet maker’s listed opening diameter and panel-thickness range, then compare both with the case. The grommet should seat fully and stay in place with gentle cable movement. A grommet that is loose or forced into an incompatible opening is not a proper fit.
Is 5 mm enough space from a fan blade?
Five millimeters is a practical no-contact target, not a universal code clearance. Keep the cable outside the fan’s swept area and check again with panels and filters installed. If a cable can move into the blades, secure or reroute it.
Can I drill a hole in a tempered-glass panel?
Do not drill or enlarge tempered glass for cable routing. It can shatter during the attempt. Use a factory opening in a metal part of the case or a pass-through approved by the case maker, and keep the glass unaltered.
Can cable ties crush or damage wires?
They can if tightened too far. Use reusable ties or hook-and-loop straps at case tie points, and tighten only enough to prevent movement. Check that the strap does not flatten the cable or pull hard on a connector.
Should I use adhesive tape to hold a fan cable?
Do not rely on tape alone where a cable could enter a fan, block ventilation, or get pinched by a panel. Use the case’s tie points or another suitable mechanical route that keeps the wire secure and clear of moving parts.
How much slack should I leave?
There is no one length for every build. Leave enough slack to disconnect or reposition the component without pulling on its connector, while keeping the wire clear of fans and vents. Recheck the route after panels and filters are installed.
Do PC wiring rules set a standard grommet size?
No universal grommet size or cable-routing clearance applies to every PC case. Match the grommet to its maker’s stated opening and panel-thickness range, and follow the instructions for the case and cables. NEC 110.3(B), where applicable, is not a substitute for those instructions.
The reliable finish is a route that looks clean from the glass side and remains protected, cool, and serviceable behind it. Prefer factory openings, fit the right grommet, secure cables without crushing them, and inspect the full path again after the case is closed.
(This article was written by one of our staff writers, Michael Holloway. Visit our Meet the Team page.)
