Intel Z68 Chipset & Smart Response Technology (SSD Caching) Review
 

The problem with Sandy Bridge was simple: if you wanted to use Intel's integrated graphics, you had to buy a motherboard based on an H-series chipset. Unfortunately, Intel's H-series chipsets don't let you overclock the CPU or memory - only the integrated GPU. If you want to overclock the CPU and/or memory, you need a P-series chipset - which doesn't support Sandy Bridge's on-die GPU. Intel effectively forced overclockers to buy discrete GPUs from AMD or NVIDIA, even if they didn't need the added GPU power.

http://www.anandtech.com/show/4329/i...caching-review