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🖤 Compact power meets sleek versatility — your desk’s new centerpiece.
The Cooler Master MasterBox Q300L is a compact mini-tower PC case crafted from durable alloy steel and plastic, featuring magnetic patterned dust filters for easy maintenance, a fully transparent edge-to-edge side panel for showcasing your build, and a modular I/O panel that rotates to three orientations. It supports versatile cooling configurations including multiple fan and radiator mounts, and accommodates high-performance components with generous interior space, making it ideal for professionals seeking a stylish, customizable, and efficient PC case.










| ASIN | B0785GRMPG |
| Antenna Location | Video Games, Business, Multitasking |
| Best Sellers Rank | 35,694 in Computers & Accessories ( See Top 100 in Computers & Accessories ) 264 in Computer Cases |
| Box Contents | 1 computer case |
| Brand | Cooler Master |
| Brand Name | Cooler Master |
| Case Type | Mini-Tower |
| Case type | Mini-Tower |
| Colour | Black |
| Compatible Devices | ATX motherboard, ATX power supply, Micro-ATX motherboard |
| Cooling Method | Fan |
| Customer Reviews | 4.5 out of 5 stars 13,680 Reviews |
| EU Spare Part Availability Duration | 2 Years |
| Enclosure Material | Alloy Steel, Plastic |
| Fan Size | 144 Millimetres |
| Global Trade Identification Number | 00884102038006, 00884102095313, 04719512065488 |
| Hard Disk Form Factor | 144 Millimetres |
| Internal Bays Quantity | 1 |
| Item Dimensions D x W x H | 41.1D x 21W x 41.1H centimetres |
| Item Type Name | MasterBox Q300L mATX Case w/Magnetic Design Dust Filter, Transparent Acrylic Side Panel, Air Flow Performance by Cooler Master |
| Item Weight | 480 Grams |
| Manufacturer | Cooler Master Europe B.V. |
| Manufacturer Part Number | MCB-Q300L-KANN-S00 |
| Material | Alloy Steel , Plastic |
| Model Name | Q300L |
| Model Number | MCB-Q300L-KANN-S00 |
| Motherboard compatibility | Mini ITX , Mini ATX |
| Number of Fans | 3 |
| Number of Items | 1 |
| Other Special Features of the Product | Magnetic Dust Filters |
| Power Supply Maximum Output | 500 Watts |
| Power Supply Mounting Type | Top Mount |
| Product Warranty | 2 years |
| Recommended uses for product | Video Games, Business, Multitasking |
| Supported Motherboard | Mini ITX, Mini ATX |
| Total Expansion Slots Quantity | 4 |
| Total USB 3.0 Ports | 2 |
| Total USB Ports | 2 |
| UPC | 884102095313 884102038006 |
J**M
✔ Awesome Little Case! (with a Few Small Flaws)
Having had a larger PC case for a while I thought it was time to move to a smaller option. I liked the look of the BitFenix cases but at around the £50 mark, the CoolerMaster Q300L was just what I was looking for price and design-wise. Being able to choose where the USB and power buttons are placed is a cool idea but if you want to use it at the top (like in my setup - Pic above) you will need a USB extension to run the cable down the back of the case. There's plenty of room for cable management and the build quality is good. I have a full sized HDD at the back and there's also space for two SSD's. Having all the holes means that you don't get much airflow pressure but I haven't had any heat issues with my overclocked AMD 1700X. If you're looking at having your PC on the floor, I woudn't choose this case as it'll most likely be full of dust in a few months. For desktop, I've had it running 4 months with minimal dust although you can see a slight dust ring around the front intake fan. When setting up be careful with any fluff and this will easily get stuck into magnet dust filter mesh. If you do decide to buy the CoolerMaster Q300L, you'll also need to invest in some fans as it only comes with one medium-volume fan. LED fans looks great and I've added three plus used the included fan as a front-intake. Pros ✔ Cool Design ✔ Build Quality + Cable Management ✔ Removable Magnet Dust Filters ✔ Compact Size Cons - Only One Fan Included - Perspex Window Tint Is Very Dark - USB Cables a little short I also upgraded the CPU fan to a Arctic Freezer 7 Pro and there's plenty of horizontal room left. If you're going for a big CPU cooler, you might have to watch out with the clearance. Cheers, Jim!
T**S
Mastic cooler case
This case is really good. I use PC part picker and I highly recommend it for beginners but this case is very cheap if you can't afford a very expensive case and I had no issues I'm using it my pre-build as a home server to store all my stuff and so far it's been fine with temperature. What's good about this case? It's very small and compact and easy and it's not that heavy and the filters are easy to change.
J**S
Cheap case, does the job
This is a cheap but capable case which is suitable for some use cases. I used it for an older mini-atx motherboard (Strix 270G) and a AIO water cooler which I mounted at the front and it fit ok with no issues. This wasn't for my main PC but rather a secondary PC which I built up from spare parts I had so I wanted to keep the costs down, so this case really does the job well. It's a small case which is what I was after but the case does feel somewhat tinny, however, the air flow is good and aesthetically I don't mind it. The window is plastic which doesn't bother me at this price point, I'd say good for entry level builds.
A**B
lovely case
Great case , plenty of room for hidden cabling. came with a fan installed which I moved to the roof as an additional out with additional fans fitted to the front to provide a positive airflow, plenty of space to do so.. Has magnetic dust covers on the front and top. And a plastic side panel to show of your led,s. Fits my B450M board and RX 580 card comfortably with the SSD hidden away. A nice compact budget case that I think looks more expensive than it was.
H**T
Great little case
Bought this thing for less than £40 so for the price i can't really complain about anything. It looks great imo Nice looking and adjustable front I/O space for 140mm fans I found it easy to build in plenty of space for cable management rubber feet on the backside so can be placed sideways easily decent included fan fairly lightweight for a case only bad point is that the 3.5" slot for your HDD is in an area of no airflow behind the motherboard so it can overheat but that hasn't affected me.
R**B
Very nice case for a mATX gaming rig
I built a mid-entry level gaming PC using it. Very good natural ventilation due to fully grid like holes on top and front with decorative magnetic filters. Not sure about space for a water cooling radiator but I didn't try it. It can accommodate 2x 2.5" and 1x3.5" drives. Has one 120mm case fan with enough space to add up to 4 extra fans (RGB of course). Happy about my build, recommended when you want a case for your RGB gaming rig.
M**M
Stylish and easy to assemble
I had absolutely no problems with this case building a PC from scratch. I like the magnetic dust filters which can be peeled off according to taste, and the industrial black look, it's better than I was expecting. It has a tinted perspex side, which looks nifty when the computer is switched on. I accidentally removed too many of the rear blanking plates, which are lightly spot welded into place, so cannot be put back once removed. Just something to be aware of.
A**E
First build went well.
Probably not the best idea ever to do a tight mATX build as my first PC build but overall went well. Word of advise be careful with the power panel, I didn't realise the panel had 4 screws holding it in the case (thought it was just the 2) and removed the top plate as it came off easily only to find that it would not go back on the same again and the power button was held on by this plate (rewired my case so that the reset button is now the power button, and positioned the power button for show). Case has managed to somehow swallow 2070 super gaming X trio but this was a very tricky install (this was why the power panel had to be removed). Cooler master ml120r argb cooler fit well too but getting the pipes in the correct position was also tricky. I have 2 mf140r as intake at the front and the original 120 fan from the case positioned at the top as exhaust near the RAM. So case is very adaptable and nothing is running too hot. Lots of room in the back for cables, do not have any HDD/sata SSD (only m.2) installed though so can't comment on cable space when these are taking up space. But do have the RGB controller from the ml120r back there running all the RGB fans. Some cables can be fiddly to run (especially the CPU power cable connecting to a MSI b450m mortar max). Overall pleased with this case, looks good and functions well.
L**E
bon boitier basique
Attention aucune baie extérieure pour lecteur graveur ou accessoire lecteur de cartes intégré. Place pour un seul hdd 3.5 et pour 2 ssd 2.5. Possibilités d'usage en vertical ou horizontal avec tableau de bord déplaçable sur les 4 côtés. Filtres anti poussière aimantés.
P**L
Good Case with many options
So this q300l case was released by cooler master in 2018 This Case was q500l 2019-2020 predecessor This case has holes in top, front and bottom I had 5 fan laptop cooler on which this Case is sitting right now, my laptop had fan issues so now it's used for PC case cooling I have attached 2 arctic fans 140mm 1600rpm and 120mm ,1200rpm in front for intake 2 coolermaster fans one for exhaust (xtraflow 1500rpm) backcand one for top ( 200-1000 rpm) 1 circle fan (1000-1200) rpm My PC temp with just one exhaust fan was around 45-55 during normal usage and CPU temp was around 64-74 degrees on normal to heavy load and gpu temps were 50 - 60 degrees CPU fan was spinning at 1500 rpm max After bumping up AMD wraith Cooler fan to max fan speed of 2600 rpm in bios settings, my CPU temps went down to 50 degrees. After installing all the fans, My case temps are 36-39 degrees My CPU temp is at 42 degrees normal and at 57 on load. If your buying this case get at least 2-4 fans You can 140mm fans or radiator in the front only On top only 120mm can be attached properly I could be wrong depends on brand and size of 140mm fan My arctic fan screw holes weren't able to match on top of the case. The magnetic dust filter on top and front can be cleaned easily. The side panel is acrylic, fingerprint magnet. 2 USB 3.0 jacks in front Mic and headphones Jack with HD audio but can only do 5.1 channel not 7.1. I had to attach my 7.1 channel headphone in the back Cable management very good Lot of spaces in the back. If you have radiator then your CPU temps will get better than mine . This case should cost around 3500 rupees But I had no choice but pay up 4500 rupees Cuz it I needed it urgently. This pandemic has really screwed PC enthusiast when it comes to pricing of PC components. 4/5 My PC specs AMD 1300X 3.8ghz (2018) Sapphire pulse RX580 8gb OC lite (2020) 😑 Ballistix red 16gb (2020)😑 Cooler master 550 mwe psu (2018) Acer vgo monitor 144hz LG monitor 75hz
K**E
Cheap, compact but carefully crafted for the air access from all sides
1) Cable management that does not suck, that's a big advantage 2) Can be placed under the monitor on the desktop, rubber pieces on the long side 3) With 3 PWM-driven chassis coolers it is a silent beauty 4) Overclocked graphics card temperature is below 65°, that's very nice airflow 5) The side panel is acrylic, not glass, which is so so, but pretty fine for a budget setup 6) Buttons and USBs can be rebased at any side, but I just kept them as-is 7) Very careful and lovely use manual, showing all necessary addons for different setups 8) Loved the included rubber pieces for easy placing of the SSDs Would definitely recommend it!
D**L
Echte aanrader
Goede kast met aardig wat mogelijkheden! Had zelf een kast nodig die niet te veel ruimte innam en niet al te duur was. Ik ben positief verrast.
D**A
Gabinete ótimo, mas acrílico super fácil de arranhar.
O gabinete é ótimo e super bonito, o que mais me chamou atenção dele foi o design super compacto e a versatilidade de usar, mas apenas de ser bonito, ele tem os seus defeitos. O acrílico é super fácil de arranhar, enquanto eu estava mudando as peças do meu antigo gabinete para esse, eu deixei o acrílico encima da minha cama com todo o cuidado do mundo, porém, quando eu fui fechar o gabinete com o acrílico, eu vi um pequeno arranhão no canto inferior direito, de início eu não dei muita importância, mas com o reflexo da lâmpada do meu quarto eu achei vários e vários pequenos arranhões que só podem ser vistos na luz, eu simplesmente não entendi o que causou aquilo, já que eu tive o máximo de cuidado possível, mas para quem vai comprar esse gabinete, cuidem do acrílico! E de resto ele me agradou muito, acho incrível como a Cooler Master consegue fazer excelentes gabinetes com preços incríveis. Apesar de ser um gabinete M-ATX, tem como você colocar até 6 fans de 120mm nele que eu achei super top e bacana. Recomendo d+.
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