Hardware Reference
In-Depth Information
4.5
.
Whereas the still-born ITX format was virtually the same as FlexATX in size (which is probably why
it was discontinued before any were sold), the Mini, Nano, and Pico-ITX form factors are
considerably smaller than FlexATX, as is the mini-DTX.
To take advantage of the smaller Mini-ITX format, several chassis makers have produced small
chassis to fit these boards. Most are the shape of a small cube, with one floppy and one optical drive
bay visible from the front. The layout of a typical Mini-ITX motherboard, the ASRock M67M-ITX, is
shown in
Figure 4.19
. Nano-ITX and Pico-ITX can fit into slimline (half-U) cases that can be used
horizontally or vertically.
Mini-ITX motherboards can offer a full range of input-output ports. And, while designs that use VIA
processors typically feature soldered-in place processors and lack PCIe expansion slots, designs that
use Intel or AMD processors support a wide range of processors and feature a PCIe slot. However,
Mini-ITX and smaller motherboards in the family are not suitable when you need a highly expandable
system (most feature only one expansion slot) or when you plan to use processors with more than
100W thermal design power (TDP).
The smaller Nano-ITX and Pico-ITX motherboards use soldered-in-place low-power
netbook/embedded-class processors from VIA, Intel, or AMD.
Note
The official site for ITX information is
www.via.com.tw/en/products/embedded/
. The site
www.mini-itx.com
is often mistaken for an official site, but it is actually a vendor that
specializes in ITX systems and component sales.
Proprietary Designs
Motherboards that are
not
one of the industry standard form factors, such as any of the ATX, DTX, or
ITX formats, are deemed
proprietary
or
semiproprietary
. Most people purchasing PCs should avoid
proprietary designs because they do not allow for a future motherboard, power supply, or case
upgrade, which limits future use and serviceability of the system. Proprietary systems are disposable
PCs because you can neither upgrade them nor easily repair them. The problem is that the proprietary
parts often come only from the original system manufacturer, and they usually cost much more than
industry standard parts. Therefore, after your proprietary system goes out of warranty, it is essentially
no longer worth upgrading or repairing. If the motherboard or any component on it goes bad, you will
be better off purchasing a completely new standard system than paying many times the normal price
for a new proprietary motherboard. In addition, a new industry standard motherboard would be
newer and faster than the one you would be replacing. In a proprietary system, the replacement board
would not only cost way too much, but it would be the same as the one that failed.
Processor Sockets/Slots
The CPU is installed in either a socket or a slot, depending on the type of chip.
Starting with the 486 processors, Intel designed the processor to be a user-installable and replaceable
part and developed standards for CPU sockets and slots that would allow different models of the
same basic processor to plug in. One key innovation was to use a zero insertion force (ZIF) socket
design, which meant that you could easily install or remove the processor with no tools. ZIF sockets
