Hi I have the same mobo and have 8gb ram installed and have had no problems so far
NZXT Lexa S
Gigabyte 890GPA-UD3H (rev 2.0) motherboard
AMD Phenom II X4 965 Black Edition, Deneb Core, S AM3, 3.4GHz
8gb Crucial Ballistic DDR3 1333mhz/PC3-10600 (7-7-7-24) 1.65v
XFX HD 6970 ATI - AMD Radeon Graphics Card - 2GB
Western Digital WD6402AAEX 640GB Hard Drive SATA111 7200rpm 64MB Cache-OEM Caviar Black.
WD 250GB 3.5" SATA 6Gb/s Caviar Blue Hard Drive - 7200RPM 16MB Cache
Corsair 750 PSU
Zalman 9500
Liteon DVD Writer
24” Samsung SM2433BW Black Widescreen LCD, 1920x1200
5.1 Creative Surround Speakers
Logitech G11 Gaming Keyboard
Logitech MX516 Gaming Mouse
Windows 7 Home Premium 64bit
Epson DX8400 All in one.