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Cooler Master MasterBox Q300L Mini Tower Case

CCL Code: CAS3310
Manufacturer Code: MCB-Q300L-KANN-S00
| Manufacturer: Cooler Master

Key Features:

  • PSU not included
  • 0 x 5.25" External Bay(s)
  • 2 x 2.5", 1 x 3.5" HDD Bay(s)
  • Max MB Size: Micro-ATX

Delivery Options

Saturday 11th December via DPD Saturday

Free Delivery by Thursday 16th December

Collection Options

Monday 13th December from Local Collection Point


inc VAT

Buying in bulk or need help? Email our Business Team.


The MasterBoxQ300L is your straightforward option in the lineup of the brand new MasterBoxQ-series from Cooler Master. A series that might be small in size but excels in functionality and modularity without compromising on the thermal performance.

Although the size wouldn’t tell, the MasterBoxQ300L supports a standard ATX PSU which we don’t see often in the market with this size. Based on the different system setup, the I/O panel can be adjusted to six different locations, three options at each side of the case. You can decide which setup fits your system best.

Due to the cube design of the frame and special pattern design on the magnetic dust filter will make the chassis stand out from the rest. The combination of a practical design and the unique customizable outlook makes the MasterBoxQ300L the perfect choice for office and home usage.


  • Max GPU Length: 360mm
  • Max CPU Cooler Height: 157mm
  • Max PSU Depth: 160mm
  • Cable Routing Space: 28mm

Main Features

  • PATTERNED MAGNETIC DUSTFILTERS - Special pattern on the dust filter creates a unique outlook for the chassis.
  • MODULAR I/O PANEL - The I/O panel can be adjusted to six different locations. On both side of the body you can install the I/O panel at the front, top or bottom.
  • MULTIPLE POSITIONING OPTIONS - The case can be put in vertical or horizontal position.
  • EDGE-TO-EDGE SIDE PANEL - Show off your build through the full size transparent side panel.
  • CLEAN ROUTING SPACE - Behind the motherboard tray, it offers 28mm wide and spacy room for hidden cable management.
  • EXCELLENT THERMAL PERFORMANCE - The open design of the perforated front, top and bottom guarantees excellent thermal performance.
  • FAN AND RADIATOR SUPPORT - The front supports up to two 140mm fans and up to a 240mm radiator. The rear supports a 120mm fan or radiator and the top two 120mm fans. All to ensure you don't have to compromise on performance.

User Controls

User Controls Power


Internal Expansion Bays 2 x 2.5"
1 x 3.5"


Expansion Slots 4 x Full Height


USB Ports 2 x USB 3.0
Headphone Ports 1 x 3.5mm Jack
Microphone In Port 1 x 3.5mm Jack


Cooling System Front: Supports 2 x 120/140mm fans
Top: Supports 2 x 120mm fans
Rear: Supports 1 x 120mm fan (included)
Bottom: Supports 1 x 120mm fan
Power Supply ATX Power Supply supported


Form Factor Mini Tower
Case Colour Black
Material SECC Steel
LED Status Indicators HDD
Motherboard Compatibility Micro-ATX
Mini ITX
Width 230 mm
Depth 378 mm
Height 387 mm
Weight 3.7 kg


Warranty 2 Years

Key Features

Firewire No
Main Colour Black
Case Type Tower
USB 3.0 Support Yes
Case Form Factor Mini Tower
Power Supply Included No
Optimised for Gaming
80Plus Rated No
PSU Form Factor ATX
Display Model in Showroom No
L.E.D Fan No LED
Internal 3.5" Bay 1
Internal 2.5" Bay 2
Micro-ATX Yes
Cooler Height 157 mm
Built-in Card Reader No
USB Type-C Support No
Front HDMI No
Side Panel Type Windowed
GPU Length 360 mm
PSU Depth 160 mm
Front Audio Type Separate
Maximum Motherboard Size Supported Micro-ATX

Item Details

Manufacturer Cooler Master
Manufacturer Code MCB-Q300L-KANN-S00
EAN 4719512065488
UPC 884102038006
Condition New

Warranty Information

Warranty 2 Years

Manufacturer Information

Manufacturer Cooler Master
Manufacturer Code MCB-Q300L-KANN-S00
Questions and Answers

Do you have you a question about the Cooler Master MasterBox Q300L (Micro-ATX/Mini-ATX) Mini Tower Case (Black)?

4 / 5 17 reviews


5 months ago

Brilliant little mATX case for the money, maybe only issue is the magnetic dust filters are easy to move but not a problem if you have it in a good location


October 2020

Fantastic case for a mATX motherboard build. Perfect for budget builders.


October 2020

Decent case for the cash,

Michael Jones

October 2020

It's a good product which can be directional depending on build. Air flow could be better. But as an matx build it gets the job done and looks good when done.


September 2020

Really crap airflow, and it's impossible to unscrew the I/O panel because you just end up stripping the screws. And because the wires coming from the panel are in the way, you can't install 140mm fans at the front.


July 2020

Excellent for my micro atx build, easy cable management, airflow is good, and looks stylish


June 2020

really good case for the money


June 2020

Great for a first build!

Terry Yip

June 2020

Best cheap and cheerful case , it also can do inverted setup too.

Mr Dawid.

June 2020

It's cheap good make and overall looks good, only con is practically no space for hard drives but apart from that love it.


June 2020

Cheap but solid and easy to work with.

Janis Kazakovs

May 2020

I read lots of negative reviews about this case i can says only one it's awesome small compact case.My components feel good even my evga 1070 sc now is colder couple degrees.


February 2020

Sleek and easy to build with


October 2019

Small and very good looking, ideal for modern home pc


October 2019

Son loves it as compact shape.


August 2019

Personally think this is the best budget pc case, it has really good thermal performance, a nice aesthetic and i like that you can move the front or in this case side io. The case was really easy to build in with alot of space behind the motherboard tray. However. The front fan mounts could be changed as the holes look really wierd with rgb shining through them


October 2018

looks nice but the front and top panels are just magnetic mats. Otherwise a nice mini case for upright or laying down

Manuals and Datasheets

PDF Datasheets and Manuals

Document File type File size
Product Sheet pdf