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ATX vs Micro ATX: what the smaller board gives up
Updated Oct 25, 2026. Prices come from our catalogue and may have changed.
A Micro ATX board is a smaller ATX board, not a different platform. It runs the same CPU, the same RAM type, and the same graphics card at the same speed. What it gives up is room. It has fewer expansion slots, usually one or two M.2 slots instead of up to five, and weaker power delivery on the cheapest boards. A Micro ATX board measures 244 by 244 mm against 305 by 244 mm for ATX, so it fits in any ATX case, but an ATX board does not fit a Micro ATX case. Micro ATX also costs less, $130 against $230 at the median in our catalogue.
Key differences
| Criterion | ATX | Micro ATX |
|---|---|---|
| Median price in our catalogue | $230 | $130 |
| Board size | 305 by 244 mm, the full ATX specification size | Square format (244 by 244 mm), the maximum size the Micro ATX specification allows |
| Case fit | Needs an ATX or larger case, does not fit a Micro ATX case | Fits Micro ATX cases and also any ATX case, since its mounting points are a subset of the ATX layout |
| Expansion slots | Sized for up to seven slots, most boards use six for a mix of full-length and smaller cards | Limited to four slots by the specification, and one to four PCIe x16-length slots in our catalogue |
| M.2 storage slots | One to five M.2 slots in our catalogue, most boards carry two to four | One or two M.2 slots in our catalogue |
| RAM slots | Four DIMM slots on every ATX board in our catalogue | Four DIMM slots on most boards, but the cheapest models drop to two |
| Power delivery on entry-level boards | Entry ATX boards tend to use a sturdier VRM, with more headroom for high-core-count CPUs at full load | The cheapest Micro ATX boards often use a lighter VRM, fine for mainstream CPUs but tighter for demanding ones |
| Gaming performance with one GPU | Identical to Micro ATX with the same CPU and graphics card | Identical to ATX with the same CPU and graphics card |
Prices in our catalogue today
| Price | ATX | Micro ATX |
|---|---|---|
| Cheapest | $100 | $64 |
| Median | $230 | $130 |
Choose ATX if…
- You want a capture card, a sound card or other add-in cards next to the graphics card
- You are building on a high-core-count CPU and want the sturdiest power delivery your budget allows
- You want four M.2 drives or more, or you simply want the extra room for cabling and future upgrades
Choose Micro ATX if…
- You are building with a single graphics card and no add-in cards, where Micro ATX gives up almost nothing
- You want a smaller case, or you want to spend less on the motherboard without changing CPU or RAM
- One or two M.2 drives and four RAM slots or fewer already cover what you need
Best value ATX
- GIGABYTE B550 Eagle$110 at Newegg
A budget AM4 board with built-in WiFi 6 and two M.2 slots.
- Asus ROG Strix B650-A Gaming$140 at Newegg
An AM5 board with three M.2 slots and WiFi 6E.
- GIGABYTE B650 AORUS Elite$160 at Newegg
AM5 with three M.2 slots and three PCIe x16-length slots, with room for a card beyond the GPU.
Best value Micro ATX
- GIGABYTE B550M K$75 at Newegg
A low-cost Micro ATX board that still keeps four RAM slots and two M.2 slots.
- Asus Prime B550M-A$118 at Newegg
Four RAM slots, two M.2 slots and built-in WiFi 6.
- MSI PRO B760M-P$110 at Newegg
An Intel option for 12th to 14th Gen CPUs, with two M.2 slots and four RAM slots.
Cheapest ATX parts
- ASRock B550 Phantom Gaming 4 AC$100 at Newegg
- GIGABYTE B550 Gaming X V2$100 at Newegg
- MSI B550 Gaming WiFi6E$100 at Newegg
Cheapest Micro ATX parts
- ASRock H610 LGA 1700$64 at Newegg
- ASRock B550M-HDV$70 at Newegg
- ASRock A520M-HDV$71 at Newegg
Frequently asked questions
Can a Micro ATX motherboard fit in an ATX case?
Yes. Micro ATX mounting points are a subset of the full ATX layout and the I/O panel is identical, so any ATX case takes a Micro ATX board. The reverse does not work, because an ATX board is too large for a Micro ATX case.
Does Micro ATX hurt gaming performance?
No. With the same CPU and the same graphics card, an ATX and a Micro ATX board perform identically in games. The difference only shows up if you need more expansion slots, more M.2 drives, or a sturdier power delivery for a demanding CPU.
Do I need four RAM slots?
Only if you plan to run four memory sticks, or want the option to add more RAM later without replacing your existing kit. Most ATX boards have four slots. Some of the cheapest Micro ATX boards drop to two, which is fine for two sticks but leaves no room to add more.
Can I fit two graphics cards on a Micro ATX board?
It is difficult. Micro ATX is limited to four expansion slots by its specification, and the second PCIe x16-length slot sits low on the board, close to the case floor, which usually blocks a second full-size card.
Is Micro ATX good enough for a high-end build?
It can be, as long as you only need one graphics card. If you want several M.2 drives, add-in cards, or the strongest power delivery for a high-core-count CPU, ATX gives you more room to grow.
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