microATX Motherboard Interface Specification

microATX Motherboard Interface Specification
Version 1.2
Page 8
1.3 Benefits to Users
While offering the same benefits of the ATX form factor specification, the microATX form factor improves
upon the previous specification in several key areas.
Current trends in the industry indicate that users require a lower-cost solution for their PC needs. Without
sacrificing the benefits of ATX, this form factor addresses the cost requirement by reducing the size of the
motherboard. The smaller motherboard is made possible by reducing the number of I/O slots. The overall
effect of these size changes reduces the costs associated with the entire system design. The expected effect of
these reductions is to lower the total system cost to the end user.
Another area of improvement is the reduced size of the chassis as it sits on the user’s desk. This reduced size
improves the aesthetic value for the end user and promotes higher satisfaction with system ownership.
1.4 Benefits to Manufacturers
Through careful designing of a microATX motherboard, an OEM can capitalize on the benefits of a reduction
in total system costs. These cost savings come from a reduced-output power supply (see the separate
documents SFX12V (Small Form Factor with 12V Connector) Power Supply Design Guide and TFX12V
(Thin Form Factor with 12 V Connector) Power Supply Design Guide, reduced chassis costs, and minimal
redesign of existing ATX 2.1 or later
1
compliant chassis for backward-compatibility.
2
Where possible, the existing mounting locations in the microATX form factor are aligned with those that exist
in ATX 2.1
1
. This alignment reduces the possible changes to existing ATX 2.1
1
-compliant chassis and
encourages the rapid adoption of the new microATX form factor. See Section 2.2 for mounting hole
locations.
microATX benefits also include those found with the current ATX form factor: more I/O space at the rear
and reduced emissions from using integrated I/O connectors.
1.5 Mounting microATX Motherboard in an ATX Chassis
Table 2 lists the requirements to mount the microATX motherboard in the ATX 2.1
1
-compliant chassis.
Table 2: Requirements to Mount microATX Motherboard in ATX 2.1
1
-compliant Chassis
Feature Status Comment
Provide motherboard mounts at location R
and S.
R required for full-width
microATX board (9.6
inches) and S optional.
See Figures 2 and 3 and Section 2.2 for
details.
Remove standoffs from any location not
defined in microATX specification or use
removable standoffs.
Required To avoid damage to the traces on the
microATX motherboard.
Verify that the chassis keepout in Area A
is adequate to prevent mechanical
interference with the chassis structure.
Required See Table 6 and Figure 7.
1
Throughout this document, references to ATX 2.1 refer to ATX Version 2.1 or higher.
2
Current ATX 2.1 chassis require additional motherboard mounts for compatibility with microATX.