
















🖤 Compact power, modular style — build your dream rig without limits!
The Cooler Master MasterBox Q300L is a compact yet highly versatile Micro-ATX tower featuring a modular I/O panel with six adjustable positions, a transparent acrylic side panel for showcasing your build, and a fully ventilated design optimized for superior airflow. It supports large components including CPU coolers up to 159mm, GPUs up to 360mm, and standard ATX power supplies, all while incorporating magnetic dust filters for easy maintenance and a distinctive look. Perfect for professionals seeking a stylish, functional, and future-proof PC case.

















| ASIN | B0785GRMPG |
| Best Sellers Rank | #4 in Computer Cases |
| Brand | Cooler Master |
| Color | Black |
| Customer Reviews | 4.5 4.5 out of 5 stars (13,757) |
| Date First Available | December 5, 2017 |
| Department | Computer Cases |
| Is Discontinued By Manufacturer | No |
| Item Dimensions LxWxH | 15.39 x 9.06 x 15 inches |
| Item Weight | 1.06 pounds |
| Item model number | MCB-Q300L-KANN-S00 |
| Manufacturer | Cooler Master |
| Number of USB 3.0 Ports | 2 |
| Product Dimensions | 15.39 x 9.06 x 15 inches |
| Series | Q300L |
| Wireless Type | 802.11a |
M**T
Good Budget friendly micro-atx case
Great value micro-atx case. Its cheap and works. Like the compact size and the fact it came with screws, spacers, ties and a fan. I like the magnetic dust filters concept however BEWARE of the very rough and pointed edges which could cut you while handling them. The power button on the side panel worked for me but could be a problem with other builds. I was barely able to fit two Thermalright TL-C14C 140mm fans in the front with the default front facing power button+LED panel layout, while managing the power/led/usb cables in between the two fans to the backpanel but it was a very tight fit. You can move the power panel to top bottom or rear if you have the space. My Thermaltake Smart 700W PSU blocked the bottom though. While the top was blocked the height and size of the Thermalright Phantom Spirit 120 SE Black CPU Cooler. And the rear was blocked by case fan and no real access for cable management through to the back panel. So I had to make the front faced orientation to work, which it did. All in all I am happy with the value of the product.
F**A
Amazing Case For an Amazing Price! (Model: Q300L)
So first I'd like to state that this review is specifically for the Q300L model. Amazon does this annoying thing where they mix all the reviews of all the models together and I can't stand it so I'm just stating the model flat out. I just built my 10 year old nephew’s PC using this case and I have to say that I was very surprised at how much I loved building in this case. Originally I bought the Compucase HEC HX300 case for 30$ from Newegg and I was just frustrated at the lack of air flow from that case. It only had room for one fan which was the back exhaust and that's it. It didn't even have holes for the power supply's intake fan! It was my fault for not researching enough and buying something so cheap. Then I did a little research and came across this case. It is only 50$ but has everything I want. I've seen PC builders on youtube build with this case and they all had great things to say. So the first thing I like about this case is obviously how much airflow it allows. It's an interesting design because there are holes all over the top, all over the bottom, and all over the front and you can install 4 fans if you wanted to (2 up top, 2 in front, 2 in bottom) in addition to the included exhaust fan at the back making it support up to 5 fans! Now with all those holes you might be thinking this is going to be an ugly case but as you'll see in the pictures this is not the case (pun intended) and it has very sleek looking dust filters to cover the top, front, and it’s not obvious from the picture but it has a filter on the bottom as well. I was pleasantly surprised to see that the filter is magnetic which made removing them to install my fans a breeze (pun intended). I also imagine cleaning them when they get dirty will also be very simple. You can simple remove them and just rinse with water. One tip when installing fans is that since there’s air holes all over, they actually made a very small indentation around the holes that you should screw in your fans. These “guides” are hard to notice but if you look closely you’ll see them. They have space for 140mm and 120mm fans depending on whatever you want. Air is able to easily flow through the filter so my air flow issues were resolved! The case also looks very nice in my opinion. I have the black model just because that’s what my nephew wanted but in review videos I’ve seen, the white one looks very nice as well. Cable management at the back is pretty good too and the case comes with a lot of zip ties. The filters I mention above are also very aesthetically pleasing. The power button, 2 USB ports, headphone jack, and speaker jack are on the side which I don’t mind. The interesting thing is that this IO panel can be unscrewed and moved to the other side which is nice. The clear side panel is acrylic but it’s a 50$ case so it’s fine. It doesn’t look bad at all. There’s also room in the cable management area for a 3.5” hard drive and 2 SSD’s inside the main area which is very good. Overall the case was pretty simple to build in. It’s designed very well to maximize airflow while looking great. I think this is an excellent case especially for the price. If you’re in the market for a cheap but good PC case, then you my friends have stumbled on a cheap but GREAT PC case. I would highly recommend this case and am willing to do even more expensive builds with this case in the future. One final note I’ll add, I built my nephew’s pc with a Ryzen 5 1600 processor and RX 480 gpu reference model targeting 1080p gaming and the heat in my old case with that one exhaust fan was reaching around 87 degrees C. After I added two intake fans in the front and one exhaust fan in the top along with the back exhaust fan that comes with this case my temperatures went down into the mid 70’s while gaming which is great. If you want looks as well as functionality for a great price, go with this case.
A**X
Pretty, but do NOT buy this for your first build
I love this case. I hate this case. Such wonderful and hateful things to say about the same case. Lets review. The good: This case is pretty. I love the aesthetics of this case. It's also very compact. It looks like a midget compared to my old Coolermaster HAF 900 series case. That's nice, since I get a lot more room on my desk, and I can position this tower in places I couldn't fit my old one. It's allowed me to do some really cool things with my desk setup that I couldn't do before. The dust covers are pretty, and they make it much easier to clean the case more frequently. (You'll still need deep cleaning every once and a while.) The bad: Boy oh boy does it suck to install things in this case. Like, cable routing is a FREAKING NIGHTMARE. If you don't care about that stuff, then it's still going to suck working in this case. "Cheap crap" is a nice description of everything about this case. The window? Cheap plexiglass that scratches easily. The PCI-E holes at the back of the case require you to pull them off using excessive force, potentially risking bending the thin metal between the slots. I ended up bending the back PCI-E screw pannel by overtightening the screws. Airflow? Gamer's Nexus tested the Q500L version of the case, and it was literally the worst case they ever tested for air flow. It caused components to thermal throttle (read: slow your computer down) at even low workloads. The Q300L is better, but it's still not winning any competitions. NEVER buy the Q500L. That seems like a long list of negatives, and it is. But I haven't gotten to the worst sin this case commits: Cable routing. I'm sure this is better than some other cases out there, but it's still pretty bad. Let's enumerate the problems you'll likely run into when routing cables: The movable button panel doesn't stretch long enough to route in convenient locations. The only place to run cables to the top of the case is a small hole that doesn't fit a standard power connector without causing you crazy amounts of grief and bending the plastic connectors while tearing chunks of flesh off your finger as you pull it through. There's not enough room on the back of the case to run your standard SATA cables for SSDs, and installing front fans means you lose out on a lot of potential cabling options. (You HAVE to move the button panel to the bottom/top if you use front fans) Why did I get this? I couldn't find a reasonably priced small sized case to put a Threadripper build in. I could have sprung for one of the smaller cases designed for compact builds, but each one of them had a deal-breaking problem. (Out of stock, couldn't fit micro-atx mobo, costs like 400$, etc.) I knew what I'd suffer through to get all the hardware to fit inside this case, while running custom cables for aesthetics. I consider it a worthwhile purchase. I spent several extra hours building this when compared with a case that was well designed. I ran into like 20 different configurations where things barely didn't fit by a millimeter or less, and the current configuration fits because I spent like 3 extra hours cabling this monster. But it was cheap, pretty, and small, so I'd probably do it again. Probably not the right case for you. Overall: This is a cheap case. It's an affordable place to put your computer. Don't expect much more than that. You can spend like 20$ more to get something truly worth holding your components.
K**S
I am Pleased
awesome case great airflow and space the only thing is space for hdd or ssd you will have to make it work if you want a clean looking case and i wish this case had a cover for the psu but all in all i love the case and the airflow of this case definitely worth the money very solid built
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+.
C**N
Ottimo case, non pensavo che spendendo poco più di 60 euro potessi avere un gioiellino simile, le dimensioni sono ridotte ma l'airflow è eccellente a patto di acquistare qualche ventola aggiuntiva in quanto abbiamo solo una 120 sul posteriore che fa comunque egregiamente il suo dovere. Supporta schede madri mini-itx e micro-atx (il mio caso) e dentro ci sta tutto. Come si vede dalla foto ho installato una GPU bella grossa, una asus dual 6700xt lunga 30 cm e un dissipatore bello generoso, un cooler master 212 alto 16 cm (ci va a pelo quindi controllate bene l'altezza del vostro dissi prima dell'acquisto).Il cable management è abbastanza agevole soprattutto in relazione alle dimensioni ridotte. Per quanto riguarda la PSU ci va un normalissimo ATX mentre per i dischi entrano tranquillamente due ssd da 2.5" e un HD da 3.5" ma il suo posizionamento sul fianco destro del case non mi convince appieno per motivi di mancanza di areazione. Due filtri a calamita con una bella trama a nido d'ape sono posti sul front e sul top mentre un terzo e posto alla base. L'unica pecca a mio avvisono è la "placchetta" dei pulsanti di accensione/reset e delle prese usb che sembra essere un pò fragilino ma posizionabile su tutti e 4 i lati del pannello.Il pannello laterale è in plastica, fosse stato in vetro temperato sarebbe stato veramente il top anche se a questo prezzo forse sarebbe stato pretendere troppo. Se cercate un case bello esteticamente esteticamente e curato nei dettagli non posso che consigliarlo.
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