HD i5 3570k is a specific version of the Intel HD 4000 Graphics that comes with the CPU 'Core i5-3570K 3.4GHz'.
The new features include DirectX 11 and Tessellation support. Using Tesselation might not be a very good idea since even strong fast-middle-class GPUs struggle with it.
The core-clock is initially set at 650MHz and will go to up to 1150MHz, if necessary.
The performance depends a lot on the driver support and benchmarks indicate that the most demanding games, such as Metro 2033 ran fluently from low to medium settings, while demanding modern games, such as Skyrim V might be playable at high settings, depending on the resolution used.
Benchmarks also indicate that the performance also depends a lot on the resolution used in a way FPS might go from 45 (1366x768) to less than 20 with 1680x1050. Therefore, the best resolution to use is 1366x768 or less.