I would agree with those numbers for the most part. I have a total of 9 of those sapphire 5830's and mine average 325 mhash's with no crashes. They are not reference cards so they don't overvolt but I have mine set at 1005 on the core and 300 on the memory using the phoenix miner with phatk aggression=13 vectors bfi_int worksize=256. And they do not get very hot compared to most other cards mine are rarely over 60 degrees even at 1005 megahertz when the fan is 100%. At 100 dollars the 5830 is the best ROI you can get.