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VIA's Mini-ITX Motherboard How VIA's tiny new motherboard design lets you build a computer that fits virtually anywhere

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VIA's Mini-ITX Motherboard
How VIA's tiny new motherboard design lets you build a computer that fits virtually anywhere

Introduction

Its been over seven years since the last significant form factor for PC motherboards, the ATX platform, was introduced. The ATX platform, and its smaller sibling, the micro-ATX, have served the traditional PC system and upgrade community well, offering lots of high-speed PCI expansion slots, an AGP video on most recent designs, and a cluster of built-in legacy and high-performance ports at the rear of the system. However, even the three or four-slot micro-ATX form factor is far too large for so-called embedded or appliance computing, which seeks to put the power of a PC in digital media devices, home entertainment centers, and other non-traditional locations. While Intel has developed the FlexATX form factor as a reduced-size version of the popular micro-ATX form factor, even FlexATX is too bulky for many embedded uses. Enter VIAs innovative Mini-ITX, which combines a form factor that's even smaller than FlexATX with low power VIA processors to provide manufacturers with the ability to put a computer almost everywhere.

Features of Mini-ITX

The Mini-ITX form factor (there is no full-size ITX) looks like what youd have if you took a micro-ATX motherboard and cut it down to a 170mm (6.69 inch) by 170mm square. Within this tiny area, a Mini-ITX motherboard still offers one PCI slot; typical ATX ports including serial, parallel, USB, network, PS2 mouse and keyboard; one or two SDRAM sockets; a two-chip chipset, and a choice of embedded processors that includes VIAs C3 or the ultra low-power Eden. Floppy and ATA host adapters enable the motherboard to connect to traditional internal mass storage devices. Theres also room for VIA EPIC networking and audio codec chips and an optional TV-out chip. Figure 1 is a simplified diagram of the VIA EPIA-V Mini-ITX motherboard.


(Click for Larger Image)

Figure 1

The basic layout of a typical Mini-ITX motherboard.

  1. PCI slot
  2. VIA VT8231 South Bridge chip
  3. VGA & audio ports
  4. USB & 10/100 Ethernet ports
  5. Parallel & serial ports
  6. PS/2 mouse & keyboard ports
  7. VIA C3 processor (fan and heatsink removed)
  8. VIA PLE133 North Bridge with passive heatsink
  9. PC133 DIMM memory sockets (2)
  10. ATX 20-pin power supply connector
  11. ATA-100 host adapter
  12. Floppy controller


(Click for Larger Image)

Figure 2 is the block diagram for the EPIA-V motherboard.

As you can see from Figures 1 and 2, Mini-ITX motherboards offer a full range of input-output ports and are comparable in features to typical entry-level systems. However, there are several differences between Mini-ITX motherboards and normal ATX-type motherboards, including:

  • The processor on a Mini-ITX motherboard is permanently attached to the motherboard with an enhanced ball-grid array (EBGA) connector, similar to the way North and South Bridge chipsets are attached to typical motherboards.
  • There is no provision for replacing on-board video with an AGP video card

Consequently, when you select a Mini-ITX motherboard, you must make sure you select the appropriate processor type and speed needed for the task you need it to perform; choose the wrong processor, and the entire motherboard must be replaced. Fortunately, VIA offers two different types of processors in several speed ranges for different tasks as well as different chipsets, enabling you to choose a motherboard with the features needed for a particular task.

C3 or Eden? Choosing the Right Processor

Both the VIA C3 E-series and the VIA Eden are x86-compatible processors, so they run the same operating systems and applications as typical AMD and Intel processors, including Windows and Linux. However, the C3 and the Eden processors are significantly slower than the Pentium 4 and Athlon XP processors found in typical desktop and notebook computers. Table 1 provides technical information about these processors.

Table 1-VIA C3 E-Series and Eden Processors

Processor Model

Clock Speed

FSB Speed

Voltage

Cache Sizes

Eden ESP 4000

400MHz

100MHz

1.05v

L1: 128KB
L2: 64KB

Eden ESP 5000

533MHz

133MHz

1.20v

L1: 128KB
L2: 64KB

Eden ESP 6000

600MHz

133MHz

1.20v

L1: 128KB
L2: 64KB

C3 E-series

733MHz

133MHz

1.35v

L1: 64KB
L2: 128KB

C3 E-series

800MHz

133MHz

1.35v

L1: 64KB
L2: 128KB

C3 E-series

866MHz

133MHz

1.35v

L1: 64KB
L2: 128KB

C3 E-series

933MHz

133MHz

1.35v

L1: 64KB
L2: 128KB

The Eden ESP series of processors use a simplified design that is optimized for the most common operations. Eden ESP processors are an excellent choice for set-top boxes and Internet clients, but the Eden ESP processors are not as powerful in features or clock speed as the C3 E-series. VIA recommends Eden processors for embedded systems, since the processor can be operated without a fan, using a passive heatsink for cooling. For more traditional computer tasks in a small footprint, VIA recommends the C3 E-series, which has performance similar to Intel Celeron processors running at similar speeds. While C3 E-series processors can also be run with a passive heatsink, they run hotter than Eden-series processors because they use higher voltages. VIA recommends a heatsink with cooling fan (an active heatsink) for C3 E-series processors unless the case is specially designed to provide adequate cooling for the processor.

Chipsets for Mini-ITX Motherboards

VIA uses varying combinations of North Bridge and South Bridge chips in its Mini-ITX motherboards. The North Bridge Chips include the PLE133 and CLE266, while the South Bridge Chips include the VT8231 and VT8235.

The PLE133 North Bridge chip features built-in Trident AGP 4x video and support for PC100 and PC133 SDRAM memory, while the CLE266 features built-in S3 Savage 4 4x AGP video, a built-in MPEG2 decoder for excellent DVD playback and support for DDR266 SDRAM memory.

The VT8231 South Bridge chip features AC97 audio, MC97 modem, an ATA-100 host adapter and four USB 1.1 ports. Additional capabilities can be added through optional chips. The VT8235 South Bridge chip features 6-channel audio, an ATA-133 host adapter, USB 2.0 ports, 10/100 Ethernet, PCI controller, and MC97 modem. It also supports the new 8X V-Link interface with the North Bridge.

Mini-ITX Motherboards from VIA

Currently, VIA offers three Mini-ITX motherboards through its VIA Platform Solutions Division (VPSD):

  • EPIA
  • EPIA V (Figures 1 & 2)
  • EPIA M

Table 2 summarizes the differences in these motherboards.

Table 2-VPSD Mini-ITX Motherboards

Model

North Bridge

South Bridge

Memory Type, # of Modules

ATA Type & Ports

USB Type & Ports

IEEE-1394a

Floppy

EPIA

PLE133

VT8231

PC100 or

PC133 (2)

100,66 (1)

USB 1.1 (4)

None

No

EPIA V

PLE133

VT8231

PC133 (2)

100, 66 (2)

USB 1.1 (2)

None

Yes

EPIA M

CLE266

VT8235

DDR266 (1)

133, 100, 66 (2)

USB 2.0 (2)

2

Yes

The EPIA M motherboard is the most sophisticated of the three, and would be the best choice for digital multimedia, thanks to its faster memory subsystem, USB 2.0 and IEEE-1394a ports, and optimized DVD playback. If you dont need the performance of the EPIA M, the EPIA V is a good choice, especially if you want to use an onboard floppy drive.

Is a Mini-ITX In Your Future?

Obviously, with top performance only on a par with sub-1GHz Celeron systems, Mini-ITX motherboards are not intended for power user or even typical desktop PC applications. However, if you need a compact system for specialized uses such as home entertainment centers or for small-footprint computers for office suites and Internet access, these tiny motherboards can be very useful.

A number of vendors produce bare-bones systems and cases designed especially for Mini-ITX motherboards, but the popularity of case modding and the possibilities inherent in a tiny form factor have helped to unleash the creativity of many individuals. A tour of the Internet reveals that dedicated hardware modders are slipping Mini-ITX motherboards into all sorts of unlikely locations, including obsolete video game system enclosures (Sega Saturn and Atari 2600), 2-slice toasters, cigar humidors, briefcases, and many more. You can see a few of the results at http://www.via.com.tw/en/VInternet/casemods.jsp, and while many of them are quite funny, they make the point that the Mini-ITX form factor makes putting a computer practically anywhere a reality. If youre looking for even more inspiration, be sure to stop by http://www.mini-itx.com, where small is big. This website specializes in news, reviews, and projects based on Mini-ITX motherboards.

VIA Product Websites

EPIA V motherboard
http://www.viavpsd.com/product/epia_v_spec.jsp?motherboardId=141

Original EPIA motherboard
http://www.viavpsd.com/product/epia_mini_itx_spec.jsp?motherboardId=21

EPIA M motherboard
http://www.viavpsd.com/product/epia_m_spec.jsp?motherboardId=81

Eden ESP processor
http://www.via.com.tw/en/Products/eden.jsp

VIA C3 E-series processors
http://www.via.com.tw/en/viac3/c3E.jsp

Third-party Reviews and Stories

VIA Arenas introduction to the EPIA M-series motherboard
http://www.viaarena.com/?PageID=187

Overclockers Australias review of an EPIA-M motherboard
http://www.overclockers.com.au/article.php?id=130033

Overclocking Projects puts the EPIA M9000 motherboard to work
http://ocprojects.extremecooling.org/modules.php?name=Content&pa=showpage&pid=22

Wondering how much smaller Mini-ITX is than the ATX form factor family? Irelands TechSeekers review has a great illustration along with other information
http://www.techseekers.net/modules.php?name=Reviews&file=index&rop=showcontent&id=3

Copyright©2003 Pearson Education. All rights reserved.

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