Intel Pentium 4 HT 3.6E socket: Socket 478

What the Pentium 4 HT 3.6E is

The Intel Pentium 4 HT 3.6E is a 3.6 GHz single-core desktop processor from August 2004. It runs one NetBurst Prescott core at 3.6 GHz with Hyper-Threading, so 1 core gives 2 threads. Cache is 1 MB of L2 with 16 KB of L1 on a 90 nm process with 125 million transistors. Power is rated at 115 W in a Socket 478 micro PGA package on an 800 MT/s front side bus with an 18x multiplier at up to 1.425 V.

Prescott doubles Northwood L2 from 512 KB to 1024 KB at a new 90 nm base and adds SSE3, which is why the 3.6E at 3.6 GHz pulls ahead of 3.4 GHz Northwood parts in threaded office tasks despite higher heat. Intel placed the 3.6E in August 2004 with the 3.2E and 3.4E Socket 478 Prescott parts. The chip supports MMX, SSE, SSE2, SSE3 and Hyper-Threading.

High clocks with a fast bus and a large cache suit late Socket 478 towers with DDR memory and AGP graphics. The 115 W envelope needs a stout Socket 478 cooler with strong case airflow. That is why the 3.6E shipped in performance towers with discrete graphics.

Socket and motherboard compatibility

The 3.6E fits Socket 478 performance desktops with Prescott support. It needs a 478-pin board with an 800 MT/s bus and a BIOS that lists the 115 W 3.6E. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.

Late DDR towers with 800 MT/s chipset paths are the natural match. Boards listing Pentium 4 HT 3.6E accept the chip with a 115 W cooler. Early 400 MT/s-only boards and Willamette-era power tables are not the target. The board CPU support list decides, since power delivery differs across Socket 478 generations.

Memory, PCIe and cooling

Memory is DDR1 and DDR2 through the board chipset, matched to the board DIMM sockets. The CPU has no memory controller, so the chipset sets the type and speed. Boards commonly carry DDR400 pairs for 800 MT/s Prescott parts.

An 800 MT/s front side bus ties the CPU to the chipset, while AGP and PCI hang off the chipset. No PCIe lanes originate on the die. Cooling uses the Socket 478 retention bracket with a cooler rated for 115 W. The 35 mm by 35 mm package needs even mounting pressure and fresh thermal paste.

Upgrade paths

On the same socket, a move to a Pentium 4 HT 3.4E keeps the board and memory when the support list names it. The 3.4E cuts 200 MHz and heat at the same 1 MB cache, so the existing 115 W cooler stays ample. A Celeron D such as Intel Celeron 2.0 drops cache to 256 KB and is a step down.

A move to LGA 775 needs a new board for DDR2 and PCIe graphics. LGA 775 Prescott parts such as the 5xx series carry the same NetBurst base with a new land grid package. The Socket 478 page lists the Prescott, Northwood and Gallatin range for planning.