Lian Li A3 mATX PSU Bracket Adapter for Alphacool Core 120mm Reservoir

Introduction / Description

This adapter lets you mount the Alphacool Core 120mm reservoir/pump combo vertically on the PSU bracket of the Lian Li A3 case. It was born out of a personal modding challenge: I originally planned a custom AMD 9950X3D water-cooling loop with dual 360×30 mm radiators and a 240 mm Alphacool distribution plate. A tiny 2 mm miscalculation meant that reservoir wouldn’t fit upright, and Alphacool confirmed it shouldn’t be mounted horizontally (risking cavitation). After waiting 60 days, I returned the 240 mm reservoir (keeping the pump) and switched to the 120 mm Alphacool Core. The PSU shroud was the only viable location for the reservoir, but its 105 × 105 mm mount holes didn’t match the Lian Li bracket – so this adapter was designed.

Adapter bracket 3D CAD render (Onshape) with stylized honeycomb lattice pattern. The adapter bracket is a solid one-piece design (5/8″ thick) with a stylized honeycomb lattice cutout. This reinforced structure adds rigidity while allowing airflow behind the mounted reservoir to the PSU. The honeycomb pattern keeps the part lightweight yet strong.

Purpose: Mounts the Alphacool Core 120 mm reservoir/pump vertically on the Lian Li A3 PSU bracket.
Design: Solid one-piece bracket, 5/8″ thick, with a stylized honeycomb lattice for strength and airflow.

Print Settings / Material Recommendations

Material: PETG or stronger. Carbon-fiber, fiberglass-, or metal-filled PETG is strongly recommended for durability.

Layer Height: ~0.2 mm.

Infill: 40–50% (gyroid, cubic or cross-hatch pattern advised for strength).

Supports: Not needed when printing flat on its back (honeycomb side up). Changing orientation may require support for the overhangs. Also rear inserts may require pop out depending which orientation you print the design, should be easy enough with a small flat head to pop out each small piece little by little, cleaned up any odd corners with the exacto. 

Hardware Requirements

Mounting: Fits the Alphacool Core 120 mm Reservoir's push-pin mounting hardware (uses standard M3 screws from the reservoir kit and thin M3 square nuts that I ordered off amazon (https://www.amazon.com/dp/B0BD2N9KTV)).

Installation Notes

Adapter (blue) mounted on Lian Li A3 PSU bracket (orange) in CAD. The adapter attaches directly to the Lian Li A3 PSU bracket using the bracket’s four existing mounting holes – no case modifications needed. Recessed pockets for the M3 square nuts ensure a neat, secure fit when mounting the reservoir. This alignment means the Alphacool push-pin connectors line up perfectly with the bracket.

Bracket Mount: Uses the stock Lian Li PSU-shroud holes (no drilling or extra hardware required).

Nut Retention: Includes recessed 1.8mm square nut pockets so the reservoir’s screws/nuts sit flush and tight.

Validation: Dimensions matched against Lian Li’s .stp model; a prototype print is in progress (feedback welcome!).

Licensing

License: Creative Commons CC BY-NC-SA (Attribution-NonCommercial-ShareAlike). Non-commercial use is allowed with credit to the author, and any derivatives must carry the same license.

Author Credit

Designed by 420coupe. Remixes and improvements are welcome – please keep the credit and license.