http://fotadl.htc.com/OTA_Supersonic_3.70.651.1-3.29.651.5_releasezq9ss6wyobuo26b5.zip
Here is the download source for manual download....tried tested and true
http://www.androidcentral.com/htc-evo-4g-getting-update-adds-nova-demo-game-swype
Here the info on how to install.....there is another thread with the download site