The temperature of the core is pulled from MSI Afterburner with the max reading used after a completed run off 3DMark Vantage and the Performance preset.
The new R9 290X indeed is a warm running video card. We knew that at stock with it warming to 94c. While we know some people have expressed concern, AMD has let us know that this isn't an issue at all and it's what the card is designed to run at. We don't doubt that for a second, and we even saw the new NVIDIA offerings run in the 80c range.
If you want the temperature lower, though, you can set a lower maximum through the Catalyst Control Center. It's going to come at the cost of more noise, though, and we know that the new R9 290X 4GB is quite loud, even at stock settings.