I decided to mine some ltc with my cpu while mining btc with my gpu's and noticed my btc hash rate was faster by about 15-25 Mh/s and more stable! I have no idea what the the benefits of this are, considering my cpu is water cooled, my radiator fans must be be taking away any gain I get from this lol. It might be different if your cpu is not water cooled though
. I was mining the ltc with 5 of my 6 cores, even with 1 core selected I am still gaining the same benifits. I'm sure this has been mentioned before, or it's just a normal thing that happens, some might not know this though, maybe try and see what gains you get!