PSU voltages

[slowrunner]

Should I be worried about the undervolting being shown in speedfan?

 

[4T5]

You can't trust Any program for True readings mate Temp or voltage.
Use a Probe for Temps & a Meter for Volts.

 

[semi-pro waster]

malc30 is absolutely right, hardware readings are infinitely more reliable. Software readings are rough approximations most of the time which can be useful but not something to get too hung up on.

I'd not be too worried about those readings if the PC is stable, just leave it be unless you are having problems.