LPX form factor
Encyclopedia
LPX originally developed by Western Digital, was a loosely defined motherboard
format (form factor) widely used in the 1990s.
There was never any official LPX specification, but the design normally featured the main I/O ports mounted on the back of the motherboard (something that was later adopted by the ATX
form factor), and a riser card in the center of the motherboard, on which the PCI
and ISA
slots were mounted. Due to the lack of standardised specification, riser cards were seldom compatible from one motherboard design to another, much less one manufacturer to another. The internal PSU connector was of the same type used in the AT form factor
; most LPX cases were compatible with AT power supplies, though some used models that were smaller than standard, and usually manufacturer-specific.
The specification was very popular in the early-mid 90's, and briefly displaced the AT form factor as the most commonly used. However, the release of the Pentium II
in 1997 highlighted the flaws of the format, as a good airflow was important in Pentium II systems, owing to the relatively high heat dispersal requirements of the processor. LPX systems suffered a restricted airflow due to the centrally placed riser cards. The introduction of the AGP
format further complicated matters, as the design not only increased the pincount on riser cards, but it limited most cards to one AGP, one PCI and one ISA slot, which was too restrictive for most users. Some lower-quality LPX boards didn't even feature a real AGP slot, but simply used a physical AGP slot and connected it to the PCI bus. This was seldom noticed however, as many "AGP" graphics cards of the time were in fact PCI cards internally, and did not take advantage of the features offered by AGP.
LPX was phased out around 1998. NLX was the intended successor, though many manufacturers chose MicroATX
or proprietary motherboard formats instead.
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...
format (form factor) widely used in the 1990s.
There was never any official LPX specification, but the design normally featured the main I/O ports mounted on the back of the motherboard (something that was later adopted by the ATX
ATX
ATX is a motherboard form factor specification developed by Intel in 1995 to improve on previous de facto standards like the AT form factor. It was the first big change in computer case, motherboard, and power supply design in many years, improving standardization and interchangeability of parts...
form factor), and a riser card in the center of the motherboard, on which the PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
and ISA
Industry Standard Architecture
Industry Standard Architecture is a computer bus standard for IBM PC compatible computers introduced with the IBM Personal Computer to support its Intel 8088 microprocessor's 8-bit external data bus and extended to 16 bits for the IBM Personal Computer/AT's Intel 80286 processor...
slots were mounted. Due to the lack of standardised specification, riser cards were seldom compatible from one motherboard design to another, much less one manufacturer to another. The internal PSU connector was of the same type used in the AT form factor
AT form factor
In the area of IBM compatible personal computers, the AT form factor referred to the dimensions and layout of the motherboard for the IBM AT. Like the IBM PC and IBM XT models before it, many third-party manufacturers produced motherboards compatible with the IBM AT form factor, allowing end users...
; most LPX cases were compatible with AT power supplies, though some used models that were smaller than standard, and usually manufacturer-specific.
The specification was very popular in the early-mid 90's, and briefly displaced the AT form factor as the most commonly used. However, the release of the Pentium II
Pentium II
The Pentium II brand refers to Intel's sixth-generation microarchitecture and x86-compatible microprocessors introduced on May 7, 1997. Containing 7.5 million transistors, the Pentium II featured an improved version of the first P6-generation core of the Pentium Pro, which contained 5.5 million...
in 1997 highlighted the flaws of the format, as a good airflow was important in Pentium II systems, owing to the relatively high heat dispersal requirements of the processor. LPX systems suffered a restricted airflow due to the centrally placed riser cards. The introduction of the AGP
Accelerated Graphics Port
The Accelerated Graphics Port is a high-speed point-to-point channel for attaching a video card to a computer's motherboard, primarily to assist in the acceleration of 3D computer graphics. Since 2004 AGP has been progressively phased out in favor of PCI Express...
format further complicated matters, as the design not only increased the pincount on riser cards, but it limited most cards to one AGP, one PCI and one ISA slot, which was too restrictive for most users. Some lower-quality LPX boards didn't even feature a real AGP slot, but simply used a physical AGP slot and connected it to the PCI bus. This was seldom noticed however, as many "AGP" graphics cards of the time were in fact PCI cards internally, and did not take advantage of the features offered by AGP.
LPX was phased out around 1998. NLX was the intended successor, though many manufacturers chose MicroATX
MicroATX
microATX, also known as µATX is a standard for motherboards that was introduced in December 1997. The maximum size of a microATX motherboard is 244 mm × 244 mm , but some microATX boards can be as small as 171.45 mm × 171.45 mm...
or proprietary motherboard formats instead.
External links
- LPX form factor at the PC Guide