
















🖤 Compact power, magnetic style — your build’s new best friend.
The Cooler Master MasterBox Q300L is a versatile mini-tower PC case featuring removable magnetic dust filters, modular I/O panel with three orientation options, and multiple cooling configurations supporting up to five fans or liquid cooling radiators. Its edge-to-edge transparent side panel showcases your build, while the spacious interior accommodates large GPUs and CPU coolers with efficient cable management. Designed for flexible vertical or horizontal placement, it combines compact size with professional-grade airflow and style.



























| ASIN | B0785GRMPG |
| Best Sellers Rank | 40,707 in Computers & Accessories ( See Top 100 in Computers & Accessories ) 357 in Computer Cases |
| Guaranteed software updates until | unknown |
| Item model number | MCB-Q300L-KANN-S00 |
| Manufacturer | Cooler Master Europe B.V. |
| Product Dimensions | 39.08 x 23 x 38.1 cm; 480 g |
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.
R**D
Great Value
In terms of features this case was very competitive at this price point, overall I'm impressed with the build quality and features. There aren't many good matx cases at this moment in time and the ones that do exist seem to be budget or really expensive. Pros - Nice aesthetic on dust filter. Loads of room for cable management (Even with non-modular psu's) Can position the front Io wherever you want. Very compact but plenty of building space. Good build quality. Fairly cheap. Fits very large graphics cards. Cons - Slightly scratched on inside acrylic panel. Difficult to get acrylic panel off. Could be more mounting points for ssd's/slim hdd's. Overall an excellent case for the price, looks very modern and a pleasure to build in.
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.
S**Y
Don't listen to the people who say cooling is a problem
This is probably the best case you can get for this sort of money but make sure you know what you're doing & what you actually want. I installed a b450 mobo, ryzen 3600x cpu, geforce 1660 gpu, 550 bronze p/s, 16gb 3000 mem, 2 12cm front fans, 250gb ssd & 500gb 2.5" hdd, it all fits perfectly & looks great, under extreme load it's almost silent & hasn't once gone over 65 deg, normal use 35-55. If you want a small, good looking well set up gaming rig, this is the case for you, if you want a ridiculous rgb rig with £2000 of gpu & an overclocked intel i9 .....forget it.
W**G
Case easy to work with, spacious and looks great. A+ to seller for quickly solving a minor problem
I used this for my first ever PC build; I am a wildlife photographer starting to venture into the world of wildlife videography; I built this PC for 4k video editing as my 4 year old laptop with an i7 processor and integrated GPU just wasn't up to the job, very frustrating to use. Spec for this build: - Asus Tuf B550M motherboard - AMD Ryzen 3600 CPU - Phoenix GEFORCE GTX 1660 super GPU - Corsair RM550x PSU - Western 500gb M.2 NVME primary drive - Seagate Barracuda 4gb storage drive - x3 Antec RGB cooling fans - BenQ 27 inch 4k monitor I have used Windows 10 home OS. All worked a treat and is absolutely rapid, handles the 4k editing and multiple large photoshop RAW files with ease. The case provided ample room for the above build with all cables neatly tidied away. I have space for a third 2.5 inch HDD/SSD should I require it in the future. Case looks great with the full open glass front displaying the build and RGB lighting. I don't often write reviews, however the seller was wonderful. The case originally came with one of the rubber feet missing. Not a huge issue, but all the same I wanted it to be right. I contacted the seller and within 3 days I had a replacement rubber foot in my postbox. Great service and all around a happy customer.
ブ**草
グラボやCPUクーラーの制限がほぼ無いMicroATXケースの中で比較的小型というのが選んだ理由です。 奥行きと高さがほぼ同じなので横から見ると正方形に見える感じです。 海外レビュー等では冷えないケースと言われてるようですが、わざわざ小さめなこのケースでハイエンド構成にする理由もないのではと思います。 前面に12cmファン二つ追加して(14cm2個付けれます)5700XとRTX3060のミドル構成で組みましたが、メッシュなだけあって冷却にはまったく問題ありません。 気になった点としては、元々付いている後部ファンが3ピンのものでPWM制御ができない点、それと前面や上面はメッシュですが、取り外しできる構造ではないので作業性が悪い点です。 それ以外は電源ケーブルの取り回し(裏配線)等もやりやすく簡単に組み立てることができました。 メッシュケースではASUSのAP201という強いライバルがありますが、あちらより一回り小さいという点、電源を標準的な後部取付にする点がいいところだと思います。 十分に満足できるケースでした。
P**L
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
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
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
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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