So, it wasn't so straightforward after all.
My fully up-to-date iMac says it's 8:54AM CDT in the twin cities now.
It's actually 7:54AM CDT.
Blogger things it's 5:53AM, but that's because I'd never switched this blog from PST. Google has DST right, but Blogger makes me make the CST/DST choice myself.
Update 8:00AM: I switched off the automatic time setting and it reset itself to the right time, then I switched it back on. So some kind of bug in how the system clock was supposed to reset. I wonder if the Intel machines did better. (yes, they did)