This offers a bit of advice on max temperatures and voltages.
This topic is a bit sparse on the internet though because, while max temps aren't hard to find, a broader or more specific temp range is hard to find.
My board monitors CPU, Memory and MB temp and has reboot or shutdown enabled when critical temps are approaching.
Unfortunately, you can't view the real-time temp unless you're looking in BIOS.
They make products that monitor and display your temps in real-time. Usually they're made to fit in a 5.25" or 3.5" bay and range from $20 to $80.