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Socket 478b, named after its number of pin contacts, is a central processing unit (CPU) socket from semiconductor manufacturer Intel Corporation. It was mainly released in 2007 for some of the laptop personal computer (PC) chips under its Core 2 brand; the component is also called Socket P. The b suffix is meant to distinguish it from the 478-pin contact version from Intel’s main competitor Advanced Micro Devices (AMD), which is called Socket 478, or Socket N, and was released seven years earlier. Despite their similarities, the Intel and AMD sockets are not compatible with each other.
The main division of CPUs compatible with the Socket 478b, Intel Core 2, was the successor of the Pentium brand in 2006, then under its fourth iteration with the Pentium 4 as the company’s flagship brand. The Socket 478b-compatible Core 2 chips were divided into two categories. They consisted of the dual-core, or two-processing unit, 2 Duo T5xx0, T6xx0, T7xx0, T8x00, T9xx0 series; and the quad-core, 2 Quad Q9x00 series.
Intel, however, also made Socket 478b compatible with the Pentium Dual-Core, which also appeared in 2006 and became the company’s mid-range brand. More specifically, it accommodated the T2410 as well as the T23x0, T3x00 and T4x00 series. The third brand granted compatibility was the Celeron M, which is the laptop PC chip version of Intel’s low-end brand. Some members of the Core 2 Duo T5xx0 and T7xx0 series use Intel’s Socket 479, or Socket M, instead, although it is not compatible with the Socket 478b due to the one-contact discrepancy.
The contacts of Socket 478b are holes for connecting the processor to the motherboard—the component of the PC with most of its crucial connectors and features—for conducting data transfer. The socket also serves as a protective device for the CPU, preventing potential damage to it, particularly during insertion and removal. Socket 478b uses the pin grid array (PGA) form factor, which involves arranging the pin holes in an orderly, grid-like four-row format on its square-shaped substrate. A square-shaped section is cut out of the Socket 478b’s center.
The PGA variant that the Socket 478b uses, flip-chip PGA (FCPGA), means that the CPU is flipped to one side to expose the die’s back, which is its hottest part. This allows a user to place on it a heatsink to reduce the heat and thus prevent the chip’s malfunction. The Celeron M processors use the Micro FCPGA variant, which is the smaller version of PGA. Socket 478b supports data transfer speeds of 400, 533, 667, 800 and 1,066 million transfers per second (MT/s).