Micro-ATX is the middle desktop size: up to 244 × 244 mm, with up to four expansion slot positions and either four or two memory slots. It fits Micro-ATX and ATX cases alike and is often the cheapest version of a given chipset. For a PC with one graphics card and a couple of drives it gives up very little, and the boards we track are on the Micro-ATX motherboard deals page.
Cheapest Micro-ATX boards right now
All 466 Micro-ATX motherboards, with price drops and price history
Amazon Warehouse offers on Micro-ATX boards
What Micro-ATX is
Micro-ATX, also written mATX or uATX, was published in 1997 as a shorter version of ATX. It is the same width as ATX at most, 244 mm, but only 244 mm tall rather than 305 mm. It keeps the ATX rear panel position and uses mounting holes that an ATX case already has, so every Micro-ATX board fits an ATX case.
The 244 × 244 mm figure is a maximum. Many budget Micro-ATX boards are narrower than that to save cost. They fit the same cases, but the right-hand edge, where the main power connector sits, may hang past the last column of standoffs. Support that edge with your fingers when you push the 24-pin cable in.
Board makers usually mark the size in the model name. An M after the chipset, as in B650M or B760M, means Micro-ATX. It is a convention rather than a rule, so confirm the dimensions in the specification.
| Item | Micro-ATX | ATX |
|---|---|---|
| Maximum size | 244 × 244 mm | 305 × 244 mm |
| Expansion slot positions | Four | Seven |
| Memory slots | Four, or two on the cheapest boards | Four |
| Fits in | Micro-ATX and ATX cases | ATX cases |
Expansion slots and memory slots
Four slot positions sounds like plenty, but count what is usable. The graphics card goes in the top full-length slot and, being two or three slots thick, covers most of what lies beneath it. On many Micro-ATX boards that leaves one slot at the bottom edge for anything else, and a card fitted there sits right against the front-panel headers and close to the case floor or power supply cover. If you need a second expansion card, look at the slot layout in the photographs before buying.
Memory is where Micro-ATX boards split into two groups. Mid-range models have four slots, the same as ATX. The cheapest models, and all boards on entry-level Intel chipsets such as H610 and H810, have two. Two slots is no handicap for speed, but it means upgrading later replaces your modules instead of adding to them, so buy the capacity you need at the start.
Expect fewer M.2 slots, SATA ports and fan headers than the ATX version of the same board. The exact numbers vary by board, and some M.2 slots share lanes with SATA ports, so check the specification against the drives you own.
Case compatibility
A Micro-ATX board fits a Micro-ATX case or an ATX case. It does not fit a Mini-ITX case. The rule is always the same: a smaller board fits a larger case, not the reverse.
Micro-ATX cases range from compact cubes to small towers that are only a little shorter than a mid-tower, so the space saving depends far more on the case than on the board. If the aim is a smaller PC, choose the case first and check three figures: maximum graphics card length, maximum cooler height and the power supply size it takes.
Cooling and cable routing
With less board area, parts sit closer together. An M.2 slot is often directly under the graphics card, where it picks up heat, and power delivery heatsinks tend to be smaller than on ATX models. Neither matters for a mid-range processor at stock settings. Both are worth thinking about if you plan to run a high-end processor hard; motherboard VRM explained shows how to judge a board's power delivery.
Cable routing is a little tighter, mostly along the bottom edge where the audio, USB and front-panel headers crowd together under the graphics card. Plug those in before fitting the card.
Price tendencies
Micro-ATX is usually where the lowest-priced board on any chipset is found, because makers build their entry-level models in this size. In the middle of the range the saving against the ATX version of the same board tends to be small, and sometimes there is none. At the high end there is little choice: only a handful of enthusiast-class Micro-ATX boards are made for each platform. If your budget is tight, this is the size where it goes furthest; how much to spend on a motherboard explains what the extra buys as you move up.
Who should buy Micro-ATX
- Budget builders who want the lowest sensible price on a current chipset.
- Anyone building a gaming PC with one graphics card, one or two SSDs and no other expansion cards.
- Builders who want a smaller tower without the cost and compromises of Mini-ITX.
- Office and family PCs, where the entry-level two-slot boards are perfectly adequate.
Choose ATX instead if you want several M.2 drives, extra PCIe cards or the widest choice of high-end boards, and Mini-ITX if the smallest possible case is the goal. ATX vs Micro-ATX vs Mini-ITX compares all three.
What to look for when buying
- Two or four memory slots, decided before you buy memory.
- The slot layout with your graphics card's thickness in mind.
- The number of M.2 slots and whether each has a heatsink.
- Fan headers: budget boards may have only two or three, which limits a case with many fans.
- WiFi, which is often a separate, slightly dearer version of the same board. See motherboard WiFi explained.
The current list of Micro-ATX motherboard deals shows new and Warehouse prices together, and Warehouse offers covers open-box boards of every size.
Questions people ask
Will a Micro-ATX motherboard fit an ATX case?
Yes. Micro-ATX uses mounting holes and a rear panel position that every ATX case already has. The board will leave empty space below it, which does no harm.
Is Micro-ATX worse than ATX for gaming?
No. With the same chipset and comparable power delivery, performance is the same. What you lose is expansion: fewer PCIe slots, usually fewer M.2 slots and fan headers, and on the cheapest boards two memory slots instead of four.
What does the M mean in a name like B650M or B760M?
It normally marks the Micro-ATX version of a board. It is a naming habit shared by the main makers, not a standard, so check the stated dimensions to be sure.
How many memory slots does a Micro-ATX board have?
Four on most mid-range models and two on the cheapest ones. Boards on entry-level Intel chipsets such as H610 always have two. The listing and the product photographs will show which.