The GeForce GTX 550 Ti has a core clock frequency of 900 MHz and a GDDR5 memory frequency of 1026 MHz. It also features a 192-bit memory bus, and makes use of a 40 nm design. It features 192 SPUs, 32 Texture Address Units, and 24 ROPs.
Compare those specifications to the GeForce GTX 560, which features a core clock speed of 810 MHz and a GDDR5 memory frequency of 1001 MHz. It also makes use of a 256-bit bus, and makes use of a 40 nm design. It features 336 SPUs, 56 Texture Address Units, and 32 ROPs.