Take a look at the differences between the old board (left) and slim board (right).
Following speculation that a 'slim' model was in the pipeline Sony officially announced the PS3 CECH-2000 on August 18, 2009 at the Sony Gamescom press conference.
The PS3 slim (officially called the PS3 CECH-2000) will feature an upgradeable 120GB hard drive and is 33% smaller, 36% lighter, and consumes 34% less power than previous models.
The cooling system has been redesigned and Cell processor has moved to a 45nm manufacturing process. The PS3 slim will also include support for BRAVIA Sync allowing control of the console over HDMI and will run quieter than previous models but no longer has the ability to install third party operating systems such as Linux.
FCC filings also reveal a second slim model, the 250GB CECH-2000B.
System Board: Up Close
Cell processor and RSX chip up close.
The PS3 uses the Sony, Toshiba, IBM designed Cell microprocessor as its CPU, which is made up of one 3.2 GHz PowerPC-based "Power Processing Element" (PPE) and eight Synergistic Processing Elements (SPEs). The eighth SPE is disabled to improve chip yields. Only six of the seven SPEs are accessible to developers as the seventh SPE is reserved by the console's operating system. Graphics processing is handled by the NVIDIA RSX 'Reality Synthesizer', which can output resolutions from 480i/576i SD up to 1080p HD. The PlayStation 3 has 256 MB of XDR main memory and 256 MB of GDDR3 video memory for the RSX.
It was rumored that the Cell processors in the third-generation PS3s (40 GB) would move from a 90 nm process to the newer 65 nm process, which SCEI CEO Kaz Hirai later confirmed, and later to 45 nm. This change lowers the power consumption of the console and makes it less expensive to produce.
So? the original ones are 90nm, the newer ones are 65, and the slim is 45nm.
The slim does not contain the emotion engine chip, and no emotion engine emulation, so there is no PS2 backward compatibility.