HD3850 Temps

So,the 1st thing i noticed.Was when i decided to oc my gpu's with rivatuner because i wanted to use the GPU Monitor Sidebar & i noticed that my card were not oc'ed thru the overdrive function.Even though it was suppost to be oc'ed.So i clocked them both(in rivatuner)to 750/1000.Now my idle temps are 61c-65c on them & set fans at 75%.under load they run about 70c.they are the single cooler type.i've been reading that these cards are made to run at those hi-temps(true or false)?So i was thing of getting 2 of these::::::http://directron.com/acceleros1rev2.html
are they any good?