Sudden and permanent increase in CPU input voltage, core temperature and fan speed without corresponding increase in load

One of my servers shows strange change in its monitored parameters. Last Sunday evening one of voltage measures ( in0 which I think is Vcore) suddenly increased by 20% from ~1V to ~1.20V on average. There is corresponding significant increase in reported CPU core temperatures and CPU fan speed but very slight increase in CPU frequency (1.20GHz -> 1.25GHz) and CPU base load.

What could this mean? I suspect failing PSU or MB. Is there any other good explanations for such behavior? There were no changes of server hardware, BIOS setting or software at this point of time.

Server MB is Gigabyte GA-MA69VM-S2 with AMD Athlon(tm) Dual Core Processor 4450e. OS is Ubuntu 12.04.2 LTS with kernel 3.2.0-45-generic. Monitoring is done by lm-sensors 1:3.3.1-2ubuntu1. Current output from sensors command is below graphs.

k8temp-pci-00c3
Adapter: PCI adapter
Core0 Temp:   +38.0°C  
Core0 Temp:   +35.0°C  
Core1 Temp:   +35.0°C  
Core1 Temp:   +37.0°C  

it8716-isa-0228
Adapter: ISA adapter
in0:          +1.20 V  (min =  +0.00 V, max =  +4.08 V)
in1:          +1.89 V  (min =  +0.00 V, max =  +4.08 V)
in2:          +3.36 V  (min =  +0.00 V, max =  +4.08 V)
+5V:          +2.98 V  (min =  +0.00 V, max =  +4.08 V)
in4:          +3.07 V  (min =  +0.00 V, max =  +4.08 V)
in5:          +3.23 V  (min =  +0.00 V, max =  +4.08 V)
in6:          +0.10 V  (min =  +0.00 V, max =  +4.08 V)
5VSB:         +3.02 V  (min =  +0.00 V, max =  +4.08 V)
Vbat:         +3.02 V  
fan1:        1555 RPM  (min =    0 RPM)
fan2:        2860 RPM  (min =    0 RPM)
temp1:        +29.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermistor
temp2:        +34.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermistor
temp3:        +31.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermal diode
cpu0_vid:    +1.200 V
intrusion0:  ALARM

Good data/research etc. and it does look exactly like you're suggesting, something's forced up vcore by .2v - no idea why but everything afterwards is following that pattern - presumably you don't have a spare CPU to switch out to see if it's the chip or VRM right? that's all I'd suggest really, divide the problem up to see if the issue remains.