Intel DP55KG has lot of extra features compared to mainstream P55-based motherboards, especially the support for SLI configuration, support for three video cards, on-board Bluetooth controller, two additional SATA-300 ports, two eSATA-300 ports, on-board optical SPDIF input and output, FireWire ports and professional-grade on-board audio.

Although it is more expensive than mainstream products, it is not badly priced if you really need the extra features it brings. Of course if the extras won’t make any difference for you, you should stick with a mainstream model and save some money.