Stable with 2 sticks only.
I got 4 of those modules:
Corsair Dominator GT
Specs:
2 GB memory
2133 Mhz
9-10-9-27 2T
1.65v
Running with all 4 sticks, makes my computer unstable at stock speeds. With 2 modules at the time however, these modules just NUKE.
Record on overclocking and stability so far:
2 x 2 GB memory
2133 Mhz
7-10-7-24 1T
1.75v
CPU VCCIO: 1.3v
CPU VCCSA: 1.29v
Another fast configuration
2 x 2 GB memory
2133 Mhz
7-9-7-27 1T
1.75v
CPU VCCIO: 1.20v
CPU VCCSA: 1.19v