Intel Pentium 4 2.40 socket: Socket 478

What the Pentium 4 2.40 is

The Intel Pentium 4 2.40 is a 2.4 GHz single-core desktop processor from March 2004. It runs one NetBurst Prescott core at 2.4 GHz with no Hyper-Threading on this rating, so 1 core gives 1 thread. Cache is 1 MB of L2 on a 90 nm process. Power is rated at 89 W in a Socket 478 package with part numbers RK80546PG0561M. The cpu_list 110 W value differs from the table 89 W, and the table value is used here.

The 2.40A carries the A suffix for the Prescott 533 MT/s line, separating it from Northwood 2.40 parts at 400 MT/s and 2.40B parts at 533 MT/s with 512 KB. It uses an 18x multiplier at 1.287 V to 1.40 V. Intel placed it as the entry Prescott Pentium 4 on Socket 478 with 1 MB of cache, doubling the 512 KB on Northwood parts at nearby clocks. The chip supports MMX, SSE, SSE2 and SSE3.

Cache lift with a die shrink defines the appeal. The 1 MB L2 doubles Northwood cache while the 90 nm process keeps power at 89 W. That balance made the 2.40A a common office tower chip, with enough cache for multitasking without the heat of faster Prescott parts.

Socket and motherboard compatibility

The Pentium 4 2.40 Prescott fits Socket 478 desktops with DDR memory, a 533 MT/s bus and Prescott BIOS support. It needs a 478-pin board with 90 nm microcode, not just any Northwood board. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.

Office DDR towers with AGP graphics are the natural match. Intel 865 chipsets with 533 MT/s support accept the chip with an 89 W cooler. Older 400 MT/s boards need a chipset check for 533 MT/s operation. LGA 775 boards need a different package.

Memory, PCIe and cooling

Memory is DDR through the board chipset. The board sets speed and capacity, since the CPU has no controller.

A 533 MT/s front side bus ties the CPU to the chipset, while AGP handles graphics and PCI handles other cards. No PCIe lanes originate on the die. Cooling uses the Socket 478 bracket with an 89 W heatsink on the 60 mm by 75 mm pattern. Fresh paste and normal airflow suit office use.

Upgrade paths

On Socket 478 the steps are Pentium 4 2.66A and 2.80A Prescott parts with the same 1 MB cache. Celeron D 335 parts at 2.8 GHz offer a value alternative with 256 KB. Beyond Socket 478 a move to LGA 775 needs a new board, with Pentium 4 505 parts as successors. The 2.40 lifts with the lever, so swaps need no solder work.