Intel Pentium 4 HT Extreme Edition 3.40 socket: Socket 478

What the Pentium 4 EE 3.40 is

The Intel Pentium 4 HT Extreme Edition 3.40 is a 3.4 GHz single-core enthusiast processor with Hyper-Threading from February 2004. It runs one NetBurst Gallatin core at 3.4 GHz with no turbo, so 1 core gives 2 threads. Cache is 512 KB of L2 plus 2 MB of L3 with 8 KB of L1 data cache on a 130 nm process. Power is rated at 102.9 W in a Socket 478 package with part numbers BX80532PG3400F and RK80532PG0962M. The cpu_list 103 W value matches the table 102.9 W after rounding, and the table value is used here.

Gallatin adds a server-derived L3 cache to the Northwood base, which separates Extreme Edition parts from standard Pentium 4 HT parts at the same clocks. The EE 3.40 uses an 800 MT/s front side bus with a 17x multiplier at 1.575 V. Intel sold it at 999 dollars in February 2004 as the top gaming chip before dual-core designs. The chip supports MMX, SSE and SSE2 with Hyper-Threading. An LGA 775 EE 3.40 shares the model number in a land grid package with different voltage handling, so socket decides fit. This page covers the Socket 478 SL7CH part.

Large L3 cache targets games and workstations with big working sets. The 2 MB L3 keeps more textures and data on die than 512 KB standard parts, which helps at the same 3.4 GHz clock. That cache premium is why Extreme Edition parts cost more than twice the standard HT 3.40 at 417 dollars.

Socket and motherboard compatibility

The EE 3.40 Socket 478 fits Socket 478 enthusiast desktops with DDR memory, an 800 MT/s bus and a BIOS that lists Gallatin Extreme Edition parts. It needs a 478-pin board with Gallatin microcode and power delivery for 102.9 W operation. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.

High-end DDR towers with AGP 8x graphics and Intel 875 chipsets are the natural match. Boards listing the EE 3.20 normally accept the EE 3.40 with a cooler rated above 100 W. LGA 775 EE 3.40 parts need land grid boards with different power planes, even though clocks match. Forcing packages across sockets damages pins or lands.

Memory, PCIe and cooling

Memory is DDR through the board chipset, with dual channel operation on 875 boards giving full bandwidth for the large cache. The CPU has no memory controller, so chipset timing decides stability.

An 800 MT/s front side bus ties the CPU to the chipset, while AGP 8x carries graphics and PCI handles other cards. No PCIe lanes originate on the die. Cooling uses the Socket 478 bracket with a high capacity heatsink rated above 100 W and strong case airflow. The 102.9 W envelope needs clean vents and fresh paste for sustained gaming loads.

Upgrade paths

On Socket 478 the EE 3.40 tops the Gallatin line above the EE 3.20 at 3.2 GHz. Standard Northwood HT 3.40 parts at the same clocks offer a lower power path without the L3 cache. LGA 775 EE 3.40 and 3.46 parts offer land grid successors with new boards. Beyond these single cores a move to dual-core Pentium D needs LGA 775 with a new chipset. The EE chip lifts with the lever, so swaps need no solder work.