It's an IGP, not AGP.
Sandy Bridge CPUs do indeed have an integrated GPU but because of this, motherboards for these processors do not have an IGP.
There are three main types of chipsets for Sandy Bridge motherboards - H67, P67 and Z68.
With H67 and Z68, you can use the integrated GPU on the Sandy Bridge processor OR choose to buy an additional graphics card. If you do buy an additional graphics card, the one on the processor will not be used.
With P67, you HAVE to buy an additional graphics card. The one on the processor is "locked".
The Core i5-2500K has the Intel HD 3000 graphics core. Generally speaking it is a little better than the desktop version of the Radeon HD 5450. The Radeon HD 5450 is the slowest card in the HD 5xxx series and is not considered a gaming video card in a desktop system.
See following review of the Radeon HD 5450 to get an idea of what the Intel HD 3000 is capable of: