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Cooler Master · Micro-Tower · Acrylic

Cooler Master MasterBox Q300L

Mini-ITX, Micro-ATX · Black

Quality
55
Quality / price
124
Max GPU
360 mm
Amazon
$40
Cooler Master MasterBox Q300L
View Cooler Master MasterBox Q300L Gallery in high resolution
$40
Available on Amazon Updated Aug 16, 2026 Prime FBA
Overall quality55.0
Quality / price123.8
Cooling support13
$40 on Amazon Open in PC Builder Case table

Written analysis

Cooler Master MasterBox Q300L at a glance

The Cooler Master MasterBox Q300L is a Micro-Tower chassis with a acrylic side panel profile. Supported boards: Mini-ITX, Micro-ATX. Primary materials are listed as steel, plastic, and acrylic glass.

Overall quality is 55.0, summing compatibility, cooling, storage, build quality, and connectivity. Max GPU length is 360 mm. Max CPU cooler height is 159 mm. Largest radiator support is listed at 240 mm.

Best fit: Performance desktops with long graphics cards and mainstream air or AIO cooling.

Cooling and front I/O

Front ports: 1x 3.5mm Audio Jack, 1x 3.5mm Mic Jack. Dust filters: Yes.

Current value

At $40, quality / price is 123.8. Compare nearby cases of the same form factor below; clearance and panel type can outweigh a small quality gap.

Chassis data

Full specifications

Construction, clearances, cooling, storage, front I/O, and quality metrics in one technical sheet.

General

Manufacturer
Cooler Master
Case
Cooler Master MasterBox Q300L
Form factor
Micro-Tower
Side panel
Acrylic
Launch price
—
Amazon price
$40
Amazon availability
Available
Price updated
Aug 16, 2026

Construction

Material
steel, plastic, and acrylic glass
Color
Black
Side panel detail
acrylic glass
Dimensions
387 x 230 x 378mm
Weight
3.70 kg
PSU shroud
No
RGB lighting
No

Quality & value

Overall quality
55.0
Compatibility
14
Cooling support
13
Storage score
7
Build quality
11
Connectivity
10
Quality / price
123.8

Compatibility / clearances

Motherboard sizes
Mini-ITX, Micro-ATX
Max GPU length
360 mm
Max cooler height
159 mm
Max PSU length
160 mm
PSU form factor
ATX, SFX
PSU included
No

Cooling

Max radiator
240 mm
Fan support
Pre-installed Fans - Rear1x 120mmFan Support - Front2x 120/140mmFan Support - Top2x 120mmFan Support - Rear1x 120mmFan Support - Bottom1x 120mm
Radiator support
Radiator Support - Front120 / 240mm Radiator Support - Front120mm Radiator Support – Rear120mm
Pre-installed fans
Not specified
Dust filters
Yes

Storage & I/O

Drive bays
5.25" Drive Bays03.5" Drive Bays12.5" Drive Bays2
Expansion slots
4
Front ports
1x 3.5mm Audio Jack, 1x 3.5mm Mic Jack
USB-C
Not listed

Additional information

Also listed as
Q300L

Amazon

Price history

Nearby quality

Similar cases

Cases close to Cooler Master MasterBox Q300L on overall quality. Open the case table to sort, filter, and compare side by side.

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Discussion

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Vendor copy

Amazon listing details

Marketplace feature text kept for reference. Structured specifications above are the source for scores and comparisons.

Ample Interior: Explore ample interior space for Micro-ATX or Mini-ITX motherboards, ensuring easy and future expansion

Components Clearance: Accommodates CPU coolers with a max height of 159mm, GPU cards up to 360mm, and PSU up to 160mm in length.

Versatile Cooling: Maximize cooling performance with a 240mm liquid cooler and 5 fans.

Modular I/O Panel: You have the flexibility to adjust its position at the front, top, or bottom on both sides

Edge-To-Edge Panel: Show off your meticulous build through the transparent side panel with pride.

Open Thermal Design: The perforated design on all sides promotes optimal airflow and heat dissipation

Magnetic Dust Filters: The unique pattern of the dust filter adds a distinctive appearance to the case.