Here is my attempt to max out on the Gigabyte GA-990FXA-UD3 rev.1.0:
AMD FX-4170 running at 4.88GHz (22X)
RAM G.Skill Pi 4Gb (2x2Gb in slots 2 and 4) 2200MHz F3-17600CL7D-4GBPIS running at 2367MHz
CPU Core Clock at 222MHz
NB at 2442MHz (11X)
HT FSB at 2664MHz (12x)
Vdimm setting at 1.710volts
ND-VID setting at +0.100v
Vcpu at +0.075v
RAM clocks at 7-10-8-24-33
CPU cooled with Xigmatek Dark Knight
RAM cooled with G.Skill Turbulence II Dual LED Fan
SB cooled with 50mm fan
Mosfet heatsink cooled with Asus Mosfet Fan
Any attempts to get 2378 to 2400MHz may get boot to Win7x64 but unstable under load.
Hope this helps but