E-ATX vs ATX Motherboards
E-ATX is ATX made wider. ATX is a fixed 305 × 244 mm; E-ATX keeps the height and extends the width, most often to 305 × 330 mm. That extra width is where the heaviest power delivery, the most M.2 slots and the widest rear I/O go, which is why E-ATX is almost entirely a high-end and workstation format. The catch is that the standard is loose: board makers use the label for anything wider than ATX, so case clearance has to be checked against the specific board, not the label.
The verdict
E-ATX is worth it for the board rather than the size: you are buying the power delivery, storage and rear I/O that the extra width allows, not the width itself. If a comparable ATX board carries the features you need, take it and keep the wider case choice. Always check the case supports the specific board's width.
The physical difference
These are fixed standards, the same for every board of that size.
Cases, cooling and what fits
Most of what people worry about here is decided by the case, not the board.
Which case takes which board
A case is built around one board size and accepts that size plus anything smaller, never anything larger. So a case rated for the larger of these two will happily take the smaller one, using a different set of standoffs, while the reverse does not physically fit. Picking the smaller board does not commit you to the smaller case.
Cooler height and graphics card length
Both limits are published by the case, not the board, and they are the two numbers most likely to catch you out in a small build. Check the maximum CPU cooler height and maximum graphics card length on the case you have in mind before you order either part.
What you give up, in numbers
How the two sizes actually differ once you look at every board on sale, rather than at what the standard permits. Measured across 12 E-ATX and 217 ATX boards at the retailers we track (11 and 201 in stock today), and updated daily.
Where we track fewer than 15 boards on a side, the exact count is shown instead of a percentage: a rate off a handful of boards would read as more certain than it is.
The picks on each side
The cheapest board on each side, and the cheapest one that clears a floor worth clearing: enough power headroom for the socket’s top processor, and Wi-Fi 6E or better. Recalculated daily from live prices.
E-ATX
ATX
Best all-round
$118.99 · cheapest with the power headroom and Wi-Fi worth having
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Common questions
Will an E-ATX motherboard fit in an ATX case?
Usually not. An ATX case is built to a 244 mm board width, and E-ATX boards are wider. Some mid towers accept the narrower E-ATX boards, so check the case's stated maximum board width against the specific board.
Is E-ATX the same size on every board?
No, and this is the main thing to watch. E-ATX is used loosely for anything wider than ATX, with real boards ranging from about 264 mm to 330 mm. Two boards both labelled E-ATX can differ by more than 60 mm.
Is E-ATX better for gaming?
Not by itself. A graphics card performs the same in either. E-ATX boards tend to carry stronger power delivery and more storage, but so do the top ATX boards, and for a single graphics card the size makes no difference to frame rates.
Keep going
Browse every E-ATX board or ATX board with filters, put two specific boards head to head, or read up on choosing a case to fit the board you pick.