E-ATX (Extended ATX)
E-ATX motherboards are the largest and most feature-packed of all the motherboard sizes. They measure 12 x 13 inches and are designed for high-end workstations and gaming PCs. E-ATX motherboards typically have the most expansion slots, memory slots, and enhanced features such as dual CPUs and quad-channel memory support.
Pros:
– More expansion slots for graphics cards, sound cards, and other peripherals
– More memory slots for high-capacity builds
– Dual CPU support for extreme performance builds
– Quad-channel memory support for heavier workloads
Cons:
– Larger size can limit case compatibility
– Higher price point compared to smaller motherboard sizes
– Requires a larger power supply with higher wattage

ATX (Advanced Technology eXtended)
ATX motherboards are the standard size for most desktop computers. They measure 12 x 9.6 inches and are widely available and affordable. ATX motherboards are versatile and suitable for various builds, including gaming PCs and workstations.
Pros:
– Widely available and affordable
– Solid performance for most use cases
– Large enough to accommodate multiple graphics cards and expansion cards

Cons:
– Size and layout limitations may result in tighter component placement in some cases
– Fewer memory slots compared to E-ATX motherboards
– Limited support for specialized features compared to larger sizes

mATX (microATX)
mATX motherboards offer a smaller form factor than ATX motherboards but still provide enough features for most builds. They measure 9.6 x 9.6 inches and are suitable for budget builds or smaller case sizes.

Pros:
– Smaller size for cases with more limited space
– Solid performance for most applications
– Generally less expensive than larger size motherboards

Cons:
– Fewer expansion slots for graphics cards and other add-in cards
– Fewer memory slots than ATX motherboards
– Limited support for specialized features compared to larger sizes

mini-ITX
mini-ITX motherboards are the smallest form factor available for desktop computers. They measure 6.7 x 6.7 inches and are typically used in compact builds or home theater PCs. mini-ITX motherboards have only one PCIe slot limiting the number of expansion cards that can be installed.

Pros:
– Extremely small form factor for compact builds
– Low power consumption for energy-efficient builds
– Limited space usage ideal for media centers

Cons:
– Limited support for expansion cards
– Fewer memory slots compared to larger motherboard sizes
– Generally more expensive than larger size motherboards

Conclusion
Choosing the right motherboard size depends on the type of build you’re aiming to complete.