Intel Core i7-3940XM socket: Socket G2

What the Core i7-3940XM is

Intel Core i7-3940XM is an Extreme Edition quad core Ivy Bridge mobile processor that Intel released in September 2012 as the top Socket G2 part. It runs at 3.0 GHz base with turbo to 3.9 GHz, with 8 MB Intel Smart Cache and Hyper-Threading for 8 threads. Power is rated at 55 W on a 22 nm process. The 100 MHz steps over the 3920XM at both ends mark a late speed bump with the same unlocked design.

Graphics are Intel HD Graphics 4000 at 650 MHz to 1350 MHz per ARK, the highest ceiling in the mobile Ivy set. The block covers displays alone, while XM laptops pair the chip with a top 2012 discrete GPU for gaming and professional work. Memory is DDR3, DDR3L and DDR3-RS at 1333 or 1600 MT/s for up to 32 GB.

At 3.0 GHz base the chip holds all core work at desktop like speeds, which is rare for a 2012 laptop. Large bodies with dual fans carry the 55 W load, and XM firmware allows multiplier changes beyond stock. The How to find your CPU socket type guide helps confirm the socketed Extreme package.

Socket and motherboard compatibility

The Core i7-3940XM fits Socket G2 as an FCPGA988 part at 37.5 × 37.5 mm. No soldered twin exists. The board must be an XM capable Socket G2 design with late 2012 microcode and the exact 3940XM string. HM77 and QM77 class chipsets carry XM builds, but only XM firmware unlocks the multiplier for changes beyond turbo.

Cooling at 55 W needs the largest Socket G2 class with shared pipes for CPU and discrete GPU. A 45 W quad sink cannot hold XM loads for long. The Socket vs chipset: what decides whether a CPU works guide explains why the maker CPU list is the final check.

Memory, PCIe and cooling

Memory support is DDR3, DDR3L and DDR3-RS at 1333 or 1600 MT/s, two channels, up to 32 GB for 25.6 GB/s at stock. XM boards allow faster memory through overclocking. Two matched 8 GB modules feed eight threads and shared graphics. ECC is not supported.

PCI Express is 16 lanes from the CPU at PCIe 3.0, split as 1x16, 2x8 or 1x8 plus 2x4. XM laptops devote lanes to a high end card plus SSDs. Power sharing between CPU and GPU decides sustained clocks more than lane counts.

Cooling is the 55 W Extreme class with dual fans. Stock 3.9 GHz bursts need clear vents, and overclocking needs headroom beyond that. Quality paste and clean fans restore peak behavior on used XM laptops.

Upgrade paths

On Socket G2 the Core i7-3940XM tops the mobile Ivy range, so same socket moves end here. The chip itself is the upgrade for QM owners on XM capable boards, adding clocks, cache behavior and multiplier control. Memory, storage and the discrete GPU carry over. A slower Extreme comparison is Intel Core i7-3920XM.

A platform change means a new performance laptop on a newer BGA package. Keep the XM board for tuning and threaded work where the unlocked multiplier still matters.