Sticks sure, but remember CPU imc my friend:) when imc is weak, than it is so. I mean voltages not for your RAM! Also try the ram slots change to 2. Channel:)
Don´t know, i had UD3 before, and their the same, all worked fine. I uses Hyper IMC´s, with Bulldozer i can get 2450 CL8-8-8:) With stockvoltages i think you can´t set 2133 Ram:)
On 990FX the CPU plays a big roll. With sempron i cant go higher than 900, with Phenom 1000 and fx-8120 1250Mhz, and i have an ud7:)
All memory straps are working and ram overclocking with Referenztakt work too. CPU nb and nb pll need more volts. I gave my nb 1,4V.