The Cooler Master Q300L V3 is a budget MicroATX case with useful modern I/O, a tempered-glass side panel and flexible fan mounting—but it comes with just one rear fan. Tom’s Hardware reported a $44.90 MSRP in its 2026 review; treat that as the reviewed list price, not a current offer. It is a compelling low-cost option if its cooling layout and fit limits suit your parts, but budget for extra airflow if you want front intake cooling.
What the Q300L V3 is—and what it is not
The Q300L V3 is the Lite Version in Cooler Master’s QUBE product family. It supports Mini-ITX and Micro-ATX motherboards and is offered in black and white, with a tempered-glass side panel and mesh/steel construction. The black model identifier is Q300LV3-KGNN-S00; the white model is Q300LV3-WGNN-S00.
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Do not confuse it with the older MasterBox Q300L or the default QUBE 340. Those are different versions, so check the exact model name and identifier when comparing listings or consulting a manual.
Core specifications and clearances
| Feature | Q300L V3 detail |
|---|---|
| Motherboard support | Mini-ITX and Micro-ATX; no back-connect motherboard support is listed in the review specifications. |
| Dimensions | 386.1 × 230 × 388.5 mm including protrusions; 374 × 230 × 374 mm excluding protrusions. |
| Volume | 34.5 L including protrusions; 32.17 L excluding them. |
| CPU cooler clearance | 178 mm. |
| Graphics-card clearance | 366 mm without a front fan; front cooling reduces the available length. |
| Power supply | ATX PSU up to 200 mm long without a bottom fan, or 140 mm with a bottom fan installed. |
| Expansion | Four slots. The review says cards up to 3.5 slots can be accommodated, subject to card length and cooling layout. |
| Front I/O | Two USB 3.2 Gen 1 Type-A ports, one USB 3.2 Gen 2×2 Type-C port and one 3.5 mm combo audio/mic jack. |
| Filters and warranty | Dust filters at the top, front and bottom; two-year warranty. |
Check GPU fit with your cooling plan
The 366 mm figure applies without a front fan, so it is not a universal guarantee that a long graphics card will fit once you add a fan or radiator. In its test build, Tom’s Hardware found the Asus TUF RTX 4080 too long and used a shorter RTX 4080 Founders Edition instead. Measure the card and account for the thickness of the cooling hardware you plan to install.
#1 Best Overall
Drive capacity depends on the exact version documentation
The review specifications list one 3.5-inch drive or two 2.5-inch drives. Cooler Master’s product-family page separately describes one 3.5-inch position, one 3.5/2.5-inch combo position and two 2.5-inch positions, for a maximum of four. Because those descriptions differ, verify the exact Q300L V3 manual and mounting layout before choosing it for a drive-heavy build.
Cooling layout and what comes in the box
The case includes one 140 mm non-ARGB rear exhaust fan and no front intake fan. Cooler Master lists support for two 120 or 140 mm fans at the front and top, plus one 120 or 140 mm fan at the bottom and rear. Radiator support is listed as 120 or 240 mm at the front and top, and 120 mm at the rear.
Rank #2
- Ideal for Gifting
- Ideal for a bookworm
- Compact for travelling
- Front: Add intake fans or a 120/240 mm radiator; either choice takes space from the graphics card.
- Top: Supports two 120/140 mm fans or a 120/240 mm radiator. A top fan or radiator may overhang the motherboard’s top edge and VRM heatsink area, so check component clearance.
- Bottom: One 120/140 mm fan is supported. Installing one reduces the listed maximum PSU length from 200 mm to 140 mm.
- Rear: One 120/140 mm fan position is occupied by the included 140 mm exhaust fan.
The magnetic top and front filters can shift slightly when touched, according to the review. The case does not hide the PSU in a separate shroud, its cable openings lack grommets, and the reviewer would have preferred Velcro tie-downs. Those are practical compromises to weigh against the low price and mounting flexibility.
What the thermal and noise tests show
Tom’s Hardware tested the case with an Intel Core Ultra 7 270K Plus, a Thermalright Peerless Assassin 120 SE and the included fan, adding a Cooler Master MasterFan M120 when needed. The review’s method stressed CPU and GPU together for 30 minutes, idled the system for 15 minutes and also tested with fans at 100%. Its test configuration used a shorter RTX 4080 Founders Edition after the Asus TUF RTX 4080 proved too long; the motherboard limited power to around 210 W. The reviewer cautioned that the results are not directly comparable with other tested systems.
| Review result | Reported measurement and context |
|---|---|
| Noise-normalized run | About 87°C average CPU and 74°C average GPU in the stated 2026 Tom’s Hardware test setup, using two fans. The reviewer noted that this system drew less power than other test systems. |
| Fans at maximum speed | 81°C average CPU and 63°C average GPU in the stated setup. |
| Maximum noise | Around 55 dBA at one meter with the included fan and added MasterFan M120 running at full speed. The included fan’s 1,400 RPM maximum was particularly audible to the reviewer. |
These are measurements from one test system and method, not temperatures or noise levels to expect from every build. The reviewer found noise-normalized performance fine at slower fan speeds and noted that more fan capacity could improve airflow. If you prioritize quiet operation, do not assume the included fan will be inaudible at full speed; consider how many fans you need and how you will set their fan curve.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Where the value is—and what to check before buying
Tom’s Hardware reported a $44.90 MSRP and described sub-$40 pricing at the time of publication. The review page showed differing retailer price snapshots, so neither figure establishes a current sale price. Check the live listing for your region and compare the complete cost, including any extra fans you need.
Rank #4
- It may suit your build if you want an inexpensive MicroATX or Mini-ITX chassis, front USB-C at 20 Gbps, a glass side panel, or the ability to place the case vertically or horizontally.
- Check another option or budget extra if you want quiet, well-ventilated operation without adding fans; have a long GPU plus front cooling; need a long PSU and bottom intake fan together; or expect polished cable openings and extensive cable tie-downs.
- Before ordering, confirm the exact V3 model, your graphics-card length with the planned front cooling installed, radiator and motherboard-top clearance, PSU length with or without a bottom fan, drive-mounting needs and current local price.
Tom’s Hardware reviewer Joe Shields called it the Best Budget Micro ATX chassis on that publication’s Best Cases list. That is the reviewer’s editorial assessment, not a guarantee that it is the best fit for every parts list or noise preference.
Quick Recap
Best Value
- It can be a gift option
- Comes with secure packaging
- Helpful in various ways
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