Well, this is good news. I'm going to be getting rid of my Nexus 5 for one of the... Ones... here shortly. Poor speaker and microphone quality are just two things I can't deal with anymore with the Nexus 5.
Seems like HTC tried to just have the CPU running too hot, figuratively and literally. Underclock down to like....1958 max, and it should be fine then. I know my Nexus doesn't like being run at a max of 2258 for very long, if at all. I'll get random reboots on stock vanilla android, and ParanoidAndroid.