Intel Core i7-2640M vs Intel Core 2 Duo T9900 vs Intel Core i7-2620M

Sandy Bridge is the evolutionary successor of the Arrandale architecture. The most noteable improvements are the new 256Bit AVX instructions, the improved Turbo 2.0 and the integration of the graphics card into the 32nm CPU core. 

Der i7-2640M offers an integrated graphics card ( Intel HD Graphics 3000) which is clearly faster then the older Intel HD Graphics in the Arrandale CPUs. As the new GPU is included in the CPU, it is also manufactured in 32nm and shares the fast level 3 cache with the CPU cores (using a new ring bus). In the 2620M it is clocked from 650-1300MHz (Turbo Boost), and in the 2640M it should be similar.

Furthermore, an improved dual-channel DDR3 memory controller is included on the CPU die that is used by the CPU and GPU part.

Due to the improved architecture and the new Turbo Boost 2.0, the average performance of the Core i7-2640M is higher than a similar clocked Arrandale Core i7 dual core. The performance should even excel the old high-end quad core models like the Core i7-820QM.

The Intel Core 2 Duo T9900 is the theoretical successor of the Core 2 Extreme X9100 (which also clocks at 3.06 GHz) that uses less power due to the modern stepping and the Enhanced Halt State (C1E). The only advantage of the X9100 is the free multiplikator (which allows easy overclocking of the CPU).

The T9900 is a fast dual core CPU for laptops which features 6 MB of shared level 2 cache and a TDP of 35 Watt. Due to the high clock speed, modern games (in 2009) should not be limited by the CPU speed. For single threaded applications it is one of the fastest CPUs for laptops (only beaten by the new Core i7 with enabled Turbo mode). 

The T9900 uses a Penryn (Montevina Update) core that features 2 integer units, 1 floating point unit, 1 load unit, and 1 store unit in a 14-stages long pipeline. Due to the Wide Dynamic Execution Technology, the core is able to simultaneously execute up to four instructions.

The integrated Enhanced Speedstep is able to downclock the core dynamically as low as 800 MHz to save power (in idle mode).

The Core 2 Duo T9900 can be used in a Socket P socket with 479 pins: Socket P / Micro Flip-Chip Pin Grid Array (Micro-FCPGA) requires 479-pin surface mount Zero Insertion Force (ZIF) socket (mPGA479M socket) or Micro Flip-Chip Ball Grid Array (Micro-FCBGA) for surface mount (479-ball).