Socket 478 The Foundation of Intels Pentium 4 Era

Do you remember the heyday of the Pentium 4 processor? During that period, the CPU's home—the Socket 478 interface—was a hot topic among computer hardware enthusiasts. Today, we examine this once-glorious CPU socket and its role in computer development history.

Socket 478, also known as mPGA or mPGA478B, was a CPU socket featuring 478 pins. It primarily accommodated Intel's Pentium 4 and Celeron processors. Introduced in August 2001 to compete with AMD's Socket A interface (462 pins) and its Athlon XP processors, Socket 478 replaced the short-lived Socket 423. Notably, it marked Intel's final PGA (Pin Grid Array) interface for desktop CPUs before transitioning entirely to LGA (Land Grid Array) technology. By 2004, with the introduction of LGA, Socket 478 gradually faded into obsolescence.

Socket 478 primarily supported Northwood-core Pentium 4 and Celeron processors. It also accommodated early Prescott-core Pentium 4s, all Willamette-core Celerons, and select Willamette Pentium 4 models. Additionally, it supported later Prescott-core Celeron D processors (among Socket 478's final compatible CPUs) and Pentium 4 Extreme Edition processors featuring L3 cache.

While Intel's mobile CPUs also used 478-pin packaging, they required slightly different sockets—such as Socket 479, Socket M, and Socket P—which were electrically incompatible with both each other and Socket 478.

The socket worked with various memory types, including DDR SDRAM, SDR SDRAM, RDRAM, and DDR2 SDRAM, offering notable flexibility for its time.

Mounting holes for securing heatsinks to motherboards were positioned with a specific lateral spacing. Proper heatsink selection and installation proved crucial for maintaining CPU stability.

All Socket 478 CPUs (Pentium 4 and Celeron) carried mechanical load limitations. Exceeding these limits during heatsink installation, transportation, or normal use risked processor fracture and permanent damage. The specific restrictions were:

Socket 478 motherboards utilized various chipsets with distinct characteristics:

• Intel 845: Among the earliest Socket 478 chipsets, it only supported SDRAM, becoming outdated as DDR memory gained popularity.
• Intel 845D: An upgraded version adding DDR memory support for improved bandwidth and performance.
• Intel 845E: Supported higher FSB frequencies for faster Pentium 4 processors.
• Intel 845G: Integrated Intel Extreme Graphics for basic display functionality.
• Intel 845GL: A simplified version typically lacking AGP slots with reduced graphics performance.

• Intel 850: Supported RDRAM, offering high bandwidth at premium prices.
• Intel 850E: Enhanced version supporting higher RDRAM frequencies.

• Intel 865P: A mainstream chipset supporting DDR memory and AGP slots.
• Intel 865G: Featured improved Intel Extreme Graphics 2.
• Intel 865PE: A high-end model supporting faster DDR memory and overclocking.

SiS and VIA offered competitive alternatives:

• SiS 645/DX/655: Cost-effective solutions with DDR and AGP 8X support.
• VIA P4X266/A/400: Budget-oriented options with varying performance levels.

Though obsolete, Socket 478 left an indelible mark on computing history. It witnessed the Pentium 4's dominance, facilitated DDR memory adoption, and paved the way for LGA technology. This socket remains an essential chapter in hardware evolution.

Socket 478's 478-pin design supported diverse processors and memory types during the Pentium 4 era. While superseded by LGA interfaces, its historical significance in computer hardware development remains undisputed.