On Speedfan, +12V reading is 10.47, and on CPUID Hardware Monitor it is 8.18V. Despite the seemingly low voltage, I have no visible issue so far, except that 3DMark11 benshmark shows CPU performance is lower than it should have been. Should I be concerned, and ask for repair or replacement of PSU?
Speedfan and most other software voltage readers are generally inaccurate, the fact that you're getting different readings just makes things more confusing don't it ?
Check voltages in the bios, if bad there you have reason to be concerned.