Cooler Master MasterBox Q300L

Brand: Cooler Master
Model: MasterBox Q300L

$43–$47estimated range · from catalog price Jun 22, 2026

Budget mATX mini‑tower with 360 mm GPU, 159 mm cooler, 240 mm rad support, and a six‑position modular I/O panel.

TierBudget?

ReleasedMar 2018

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Form factormATX

ColorBlack

Tempered glassYes

GixCore Editorial

Product overview

Launched on March 1, 2018, the MasterBox Q300L is part of Cooler Master’s MasterBox Q‑series (the Q300 line alongside the Q300P). It’s a budget‑tier micro‑ATX mini‑tower built to keep costs down while still accepting a standard ATX PSU and full‑length GPUs.

It suits airflow builds and budget builds that still need high GPU clearance: room for 360 mm graphics cards, 159 mm air coolers, and a 240 mm front radiator. Cooling mounts include 2×140 mm front, 2×120 mm top, 120 mm rear, and 120 mm bottom. Storage is basic (1×3.5 in + 2×2.5 in). Front I/O is 2× USB 3.0 plus separate mic/headphone jacks, and the side‑mounted I/O block can be relocated to six positions. Perforated panels with magnetic dust filters and an edge‑to‑edge transparent side panel round out a simple, compact layout.

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