Intel Core 2 Duo T5500 socket: Socket M

What the Core 2 Duo T5500 is

August 2006 put the Intel Core 2 Duo T5500 into mainstream notebooks at 1.67 GHz, as a 2 MB Merom part for the opening Socket M Core 2 Duo lineup. Two cores share 2 MB of L2 cache, which is half of the 4 MB Merom die with the rest deactivated, and the 65 nm chip runs 64-bit code through Intel 64. A 667 MT/s front side bus with a multiplier of 10 gives the 1.67 GHz speed, and power is rated at 34 W. Production moved through B2, G2, and L2 steppings over the life of the part.

Virtualization buyers need to watch the stepping. The compatibility notes tie VT-x on the T5500 to the L2 stepping only, while the early B2 stepping lacks it and the T5600 plus every T7xxx part carry it throughout. Used chips therefore differ in more than clock speed, and the sSpec printed on the package tells which revision is on offer. The socketed Micro-FCPGA package uses part numbers that start with LF, while the soldered BGA twin uses numbers that start with LE, so the marking also settles the package question at a glance.

At 1.67 GHz the T5500 stood one rung above the 1.6 GHz T5200, trading the older 533 MT/s bus for 667 MT/s next to a small clock gain. Against the 1.83 GHz T5600 it gave up clock speed while keeping the same 2 MB cache and 34 W rating, so the two parts differed only in clock speed, with multipliers of 10 and 11 on the same bus. That middle seat placed the T5500 between the entry T5200 and the faster T5600 in the August 2006 lineup.

Socket and motherboard compatibility

The T5500 fits Socket M, a 478-contact lever-actuated ZIF socket for Micro-FCPGA mobile parts. Napa generation boards with 945PM or 945GM chipsets are the natural home, since that family tops out at a 667 MT/s bus that matches this chip exactly. A Core Duo era board usually needs a BIOS update with Merom microcode before the T5500 will start, because the refresh was designed as a drop-in Napa part inside the same 34 W envelope. The notebook maker CPU support list settles any doubt for a specific model, and the Socket vs chipset: what decides whether a CPU works guide explains the checks in order.

The same silicon also shipped soldered as a BGA479 part for thinner machines, and that twin cannot be removed or upgraded, so board replacement is the only remedy when it fails. This page covers the socketed Micro-FCPGA package, which lifts from its lever socket for service or for a faster chip when the BIOS allows it. The T5500 does not fit Socket P boards, because Socket P shifts one pin position and belongs to the Santa Rosa generation with its 800 MT/s parts.

Memory, PCIe and cooling

Memory on a T5500 notebook is DDR2 through the board chipset in two channels, and the machine maker fixes the slot count plus the top capacity. The 667 MT/s front side bus sets the pace between the processor and that chipset, which is the fastest bus the Napa family supports. Notebook vendors tuned their heat pipe assemblies around the 34 W rating, ending at a side vent with a fan curve set for sustained dual-core load.

The processor carries no PCI Express lanes of its own. Graphics and expansion slots connect through the mobile chipset, so chipset choice shapes display and I/O behavior more than the CPU does. Enhanced SpeedStep lowers clocks and voltage at idle and on battery, which stretches running time on machines whose cooling and cells were sized for the Napa power budget.

Upgrade paths

Inside Socket M the worthwhile steps up are the full-cache Merom parts, namely the T7200 at 2 GHz and the T7400 at 2.17 GHz, with the T7600 at 2.33 GHz closing the list. Each keeps the 34 W rating and the 667 MT/s bus, so the heat pipe assembly stays valid and only the BIOS needs to name the new part. Moving from 2 MB to the shared 4 MB cache also brings VT-x on every T7xxx stepping, which answers the virtualization gap found on early T5500 chips.

Going past Socket M means a platform change to Socket P and a Santa Rosa notebook, where 800 MT/s Merom parts and newer chipsets take over. The sockets differ by pin placement, so no chip swap crosses that line. For a T5500 machine that stays put, a memory lift to the board maximum and a fresh heat pipe service deliver the most visible gain per hour of work. The Socket vs chipset: what decides whether a CPU works guide walks through the checks.