Intel Pentium 4-M 1.40 socket: Socket 478

What the Pentium 4-M 1.40 is

The Intel Pentium 4-M 1.40 is a 1400 MHz single-core mobile processor from April 2002. It runs one NetBurst Northwood core at 1400 MHz with no Hyper-Threading, so 1 core gives 1 thread. Cache is 512 KB of L2 on a 130 nm process. Power is rated at 25.8 W in a Socket 478 package with a 400 MT/s front side bus and a 14x multiplier. The cpu_list 21 W value differs from the table 25.8 W, and the table value is used here.

The 1.40 P4-M opens the Pentium 4-M Northwood line with SpeedStep trimming voltage to 1.20 V at idle against 1.30 V to 1.55 V at full speed. Intel sold it in April 2002 as an entry notebook chip with a 35 mm by 35 mm package. The chip supports MMX, SSE and SSE2 with SpeedStep. Mobile Pentium 4 1.40? No desktop-replacement 1.40 exists at the same clocks, so the P4-M stands alone with battery savings.

Low power with a full 512 KB cache suited thin mainstream notebooks. The 25.8 W envelope with SpeedStep allows hours of battery life, while the large cache keeps office tasks responsive at modest frequency. That is why P4-M parts cost more than Mobile Celeron parts at similar megahertz despite sharing sockets.

Socket and motherboard compatibility

The Pentium 4-M 1.40 fits Socket 478 notebooks with DDR memory and P4-M BIOS support. It needs a notebook Socket 478 board with SpeedStep paths. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.

Mainstream DDR notebooks are the natural match. Maker lists decide fit, since Mobile Pentium 4 parts at similar clocks need larger cooling without SpeedStep savings.

Memory, PCIe and cooling

Memory is DDR through the board chipset with notebook slots. The CPU has no controller.

A 400 MT/s bus ties the CPU to the mobile chipset, while graphics hangs off the chipset. No PCIe lanes originate on the die. Cooling is the notebook heat pipe for 25.8 W with quiet fans. SpeedStep extends battery life.

Upgrade paths

On Socket 478 the mobile P4-M steps are 1.50 and 1.60 parts where listed. Pentium M Banias parts on Socket 479 offer far lower power for thin bodies. Mobile Pentium 4 parts offer desktop-replacement alternatives at higher power. The 1.40 removes with the socket mechanism, so swaps need no solder work.