Intel Pentium 4 HT 2.8E socket: Socket 478

What the Pentium 4 HT 2.8E is

The Intel Pentium 4 HT 2.8E is a 2.8 GHz single-core desktop processor with Hyper-Threading from February 2004. It runs one NetBurst Prescott core at 2.8 GHz with no turbo, so 1 core gives 2 threads. 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 RK80546PG0721M. The cpu_list 115 W value differs from the table 89 W, and the table value is used here.

The 2.8E opens the Prescott HT E line on Socket 478 with an 800 MT/s front side bus and a 14x multiplier at 1.287 V to 1.40 V. Intel sold it at 178 dollars in February 2004. The chip supports MMX, SSE, SSE2 and SSE3 with Hyper-Threading. An LGA 775 520 at the same 2.8 GHz shares clocks with a land grid package, so socket separates the two numbers at identical frequency.

E marks the Prescott HT generation with 1 MB of cache against Northwood HT parts with 512 KB. The doubled cache helps at the same 2.8 GHz clocks, which is why Prescott E parts replaced Northwood HT parts in new Socket 478 towers despite higher heat.

Socket and motherboard compatibility

The Pentium 4 HT 2.8E fits Socket 478 desktops with DDR memory, an 800 MT/s bus and Prescott HT BIOS support. It needs a 478-pin board with 90 nm microcode and Hyper-Threading paths. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.

DDR towers with 800 MT/s chipsets are the natural match. Intel 865 chipsets accept the chip with an 89 W cooler on the Socket 478 bracket. Older 533 MT/s boards need a chipset check for 800 MT/s operation. LGA 775 520 parts need land grid boards instead.

Memory, PCIe and cooling

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

An 800 MT/s 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. Fresh paste and normal airflow suit office and media use with Hyper-Threading enabled.

Upgrade paths

On Socket 478 the steps are the Pentium 4 HT 3.0E at 3 GHz and the 3.2E at 3.2 GHz with the same 1 MB cache. Northwood HT 2.8C parts offer a cooler 130 nm alternative with 512 KB. Beyond Socket 478 a move to LGA 775 needs a new board, with 520 parts as successors. The 2.8E lifts with the lever, so swaps need no solder work.