Intel Pentium M 750 socket: Socket 479

What the Pentium M 750 is

The Pentium M 750 filled the middle of the Sonoma Pentium M range when Intel launched it in January 2005. One Dothan core runs at 1.86 GHz without a turbo bin, so sustained work and short bursts share the same ceiling. Its 2 MB L2 cache keeps larger office documents and browser sessions closer to the core than the 1 MB Banias generation could. The silicon uses the 90 nm process with 144 million transistors on an 87 mm2 die, values TechPowerUp lists uniformly across the 730 to 780 family.

The rated speed comes from a 14x multiplier on a 133 MHz base clock, transferred over a 533 MT/s front side bus. Intel locks the multiplier, which leaves bus selection and power policy to the notebook firmware. SpeedStep steps the clock down at idle and restores full speed on demand, a behavior that defined battery life on Sonoma machines. Instruction support covers MMX, SSE and SSE2 plus the NX bit, with no 64 bit mode, so period 32 bit drivers remain the correct match.

At 1.86 GHz the 750 sat between the mainstream 740 and the faster 760 at launch. All three carry the same 27 W rating, the same cache size and the same bus rate, which makes clock the only performance split among them. Intel offered this SKU as a socketed Micro-FCPGA part described here and as a soldered Micro-FCBGA twin for socket free boards. In a used Sonoma notebook the 750 reads as a balanced pick, quicker than the entry pair without reaching the top price tier of the time.

Socket and motherboard compatibility

This processor drops into a ZIF socket with 479 holes arranged as mPGA479M and closes with a side lever. Zero force entry protects the pins during placement, then the lever draws the package into firm contact for daily thermal cycles. Only 478 positions carry signals because one site is reserved, a detail that blocks any use in Socket 478 desktop boards. Hole count and the mPGA478C label appear on the Socket 479 page.

A Sonoma mainboard on a 915 series mobile chipset gives the 750 its intended setting. That chipset family drives the 533 MT/s bus and hosts DDR2 memory beside it. The older 855 series was laid out for 400 MT/s Banias operation and stays a poor host for a 533 MT/s Dothan chip, even where insertion feels normal. The Socket vs chipset: what decides whether a CPU works guide explains the chipset and firmware checks that must pass after the physical fit.

Compatibility at the firmware level turns on the sSpec code. The 750 shipped as sSpec SL7S9, and notebook makers placed that string in BIOS support tables for each board. Missing codes can halt boot or cap the reported speed. Its Micro-FCBGA twin solders to the board through 479 balls and has no socket, so socketed buyers never meet it in the used CPU trade. The 2006 Socket M successor moved one pin for Core processors and stays electrically incompatible with these boards.

Memory, PCIe and cooling

DDR2 memory reaches the 750 only through the board chipset, since the CPU has no controller of its own. Slot number, maximum module size and qualified speeds vary by notebook model and chipset strap. Maker approved DDR2 400 or DDR2 533 modules in the documented arrangement feed the 533 MT/s front side bus during cache misses. The notebook manual gives the exact ceiling, which buyers should confirm before adding capacity.

Expansion follows the same chipset centered pattern. The processor exposes no PCI Express lanes, so the front side bus at 533 MT/s moves CPU data to the chipset and the chipset fans it out to graphics and slots. Sonoma boards either use chipset graphics or mount a separate mobile graphics chip, and drivers for either path come from the system or chipset vendor rather than from processor packaging.

Cooling comes from the notebook vendor heat pipe sized for the 27 W class. A plate over the exposed die joints to one or two pipes that exhaust through a side vent, under control of firmware fan curves written for that heat level. Because the package lacks a spreader, service calls for careful cleaning of the die face and a light uniform paste film. A cleared vent path and fresh pads on surrounding regulators bring fan noise back toward factory behavior.

Upgrade paths

Owners of a working 750 board can move inside Socket 479 when the BIOS permits. Downward the 730 at 1.6 GHz and the 740 at 1.73 GHz offer cheaper spares with less speed, while upward the 760 at 2.0 GHz, the 770 at 2.13 GHz and the 780 at 2.26 GHz raise the locked multiplier within the same cache, bus and 27 W limits. The heat pipe stays adequate across that span, so the swap centers on firmware support rather than thermals. Each candidate sSpec still needs a line in the maker CPU list.

A jump past this family calls for a platform change. Core Duo processors belong to Socket M with its revised pin and 945 series chipsets, so they need a different notebook or mainboard. The Socket vs chipset: what decides whether a CPU works guide sets out the order of checks for either route. Where the machine lags in everyday response, a memory increase and a solid state drive on the present board frequently matter more than a single multiplier step.