Default core clock is 810. I can get that up to 950 through OCing, without even messing with the voltages. Could probably get it higher though. I've read about people getting it to 1050. Temperature is at 74'C under load, with fan speed at 78%. All the latest graphics card drivers are installed along with OpenCL and SDK 2.4. With MSI Afterburner I have it set so that OC settings are applied at system start-up as well, so that is not an issue.