Does the fan included have LED on it?

No, it does not have an Led. It is a basic, three wire, fixed speed fan.

Can this hold a standard ATX board?

No. This is designed to work with micro ATX boards.

Does it come with a power supply?

No. This is a mATX case only. A power supply will need to be purchased separately. It only comes with one exhaust fan like the one you see in the product images. I recommend purchasing additional case fans in addition to a power supply.

"The case can be put in vertical or horizontal position" according to Cooler Master's website, does this include upside down?

If by upside down you mean with the power supply on top, then yes, it appears you can remove the feet, screen, etc and place them on the "top" or the "front". However, I'm not sure there are any fan screw holes on the "bottom" already.

is this a metal case?

the entire case is metal except the viewing panel,IO panel and the facade pieces on the edges

Does it come with the fan in the picture?

Hello Luke Camarillo, Thank you for contacting us in regards to your question. Yes it'll come with 1 120mm fan pre installed in the back. Thank you and have a nice day! Newegg Support

can this case hold 2x 3.5 HDD ??

Yes, but I do not recommend this case. The plastic that houses the power and peripheral ports is extremely flimsy. It is thin plastic that is only attached at the two end screws with no support behind it. Power button is very cheap and will break. Mine already has. If it wasn't for this, I would be pleased with the price point of this case.

Does this case have external drive bays?

No it does not. Everything is internal. The front and top has mesh filters for dust, but that is about it.

what do i need to add to it so it will work?

As a paperweight, Nothing. As a bare minimum computer, Motherboard, CPU, PSU, RAM, And OS. Of course, A monitor, mouse, keyboard might help as well. If you plan on gaming a GPU is recommended.

What type of connecters on the fan in the back?

Standard 3-pin fan connector, if memory serves me. Nothing special about it.

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Main image of Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 2 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 3 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 4 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 5 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 6 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 7 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 8 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 9 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 10 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 11 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 12 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 13 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 14 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 15 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 16 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 17 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 18 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

Alt view image 19 of 19 - Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

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Cooler Master MasterBox Q300L Micro-ATX PC Case - Compact mATX Computer Case with Magnetic Dust Filters, Modular Adjustable I/O Panel, Perforated Airflow Design, 1 x 120mm Pre-Installed Fan, Black

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Options: MasterBox Q300L (Black)

MasterBox Q300L (Black)
MasterBox Q300LV2 (White)

I/O panel can be adjusted in 6 different locations and the Case can be positioned: vertical or horizontal
Edge-to-Edge Acrylic Transparent Side Panel offers a full view inside
Body depth height: can support normal size ATX power supply
Front Magnetic Design Dust Filter with open perforated front, top and bottom for high air performance
Extra space behind the motherboard tray for hidden cable management

🔥Don't forget your OS, we have Windows 11 OEM, Download and USB versions available

Overview

Specs

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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, 28mm of space is offered for cable management. 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

Best Seller Ranking	#34 in Computer Cases

Model
Brand	Cooler Master
Series	MasterBox Q300L
Part Number	MCB-Q300L-KANN-S00

Details
Type	Micro ATX Tower
Color	Black
Case Material	Steel / Plastic
With Power Supply	No
PSU Mount	Bottom
Motherboard Compatibility	Micro ATX / Mini ITX
Side Panel	with Side Window
Dust Filters	Bottom

Expansion
Internal 3.5" Drive Bays	1
Internal 2.5" Drive Bays	2
Hot-Swap Drive Bays	0
Expansion Slots	4

Front Panel Ports
Front Ports	2 x USB 3.0, 2 x Audio

Cooling System
Fan Options	Front - 2 x 120mm / 2 x 140mm fan Rear: 1 x 120mm fan (Pre-installed) Top: 2 x 120mm fan Bottom: 1 x 120mm fan
Radiator Options	Front - Up to 240mm / Rear - Up to 120mm
80mm Fans	No
140mm Fans	No
Side Air duct	Yes

Dimensions & Weight
Max GPU Length	360 mm
Max CPU Cooler Height	157 mm
Max PSU Length	160 mm
Dimensions	15.00" x 9.06" x 15.24"
Weight	8.16 lbs.

Additional Info
Features	High Flexibility for System Building: 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. Minimized Dimension with ATX PSU Support: Despite the Micro-ATX form factor and the body depth and height of only 370mm x 370mm, the MasterBox Q300L can accommodate a normal ATX PSU. Patterned Dust Filter: Special pattern on the dust filter creates a unique outlook for the chassis. 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. Edgo-to-Edge Acrylic Transparent Side Panel: Show off your build through the full size transparent side panel. Vertical and Horizontal position: The case can be put in vertical and horizontal position.

Additional Information
First Listed on Newegg	October 17, 2026

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