your MoBo says dual channel supported.
Kingston is a long time memory module manufacturer - another 4GB cannot do ANY thing but help you out.
Write to Kingston and ask them what the max reccomended voltage is for their testing and i would say that MOST companies overvolt to test (industry standard - like G-Skill) and over volt no more than they tested at and MAYbe end up w/ some 1600's.
That's exACTly what i did. I wrote G-Skill and told them I was doing an "overclock special" review and would be using g-skill #xxx and they wrote me back and told me what the max spec for voltage were on my specifiv DIMMS were.
So i run my g-skill 1333's at THEIR specs for over voltage and have 1600's for an obvious cheaper price. AND they have been stable for me for over a year now.
Just keep in mind hotter means "wear and tear" but for $40... do i look like i am sweating it? (me smiling)