My miner perfect work at a frequency of 268.75 - 275, and outputs the 2500-2700 ghesh
WTF? that's pretty good. Did you have to change the voltage too? Does yours run stable with no X's for a long time?
dont believe some like this, without powerful psu thats meanless..
There is absolutely no way to push the mhz to 275 on the supplied PSU. Hell, I can't even get it to run 250mhz and I'm on 220-240v (lower amp draw) in Singapore. The best I could get it to run stable is 231.25mhz at 0725v. But watch the tempreture. Mine goes up to 63-65C which I believe is still ok (there must be a reason why the cut off is at 80c). As long as you do not switch pools, or restart (not hard reset), the X's don't appear.