Need advice on this 700 gaming build.

Mobo: GIGABYTE GA-Z77X-D3H LGA 1155 Intel Z77 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard

Video Card: SAPPHIRE Radeon HD 6870 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card (100314-3L )

PSU: Antec NEO ECO 520C 520W Continuous Power ATX12V v2.3 / EPS12V 80 PLUS Certified Active PFC Power Supply

CPU: Intel Core i5-2400 Sandy Bridge 3.1GHz (3.4GHz Turbo Boost) LGA 1155 95W Quad-Core Desktop Processor Intel HD Graphics 2000

RAM: G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9D-4GBRL

HDD: Western Digital Caviar Blue WD5000AAKX 500GB 7200 RPM SATA 6.0Gb/s 3.5" Internal Hard Drive -Bare Drive

I already have OS/KB/Mouse/Speakers/Monitor. The above totals at about 669$ before tax/shipping. I primarily need advice/alternatives on the motherboard.