How precise is HWiNFO?

Hello there!

I've been using HWiNFO to compare my PSU voltages to those I see on some reviews.

My questions is, how precise is HWiNFO voltages in comparison to Physical measured ones?

For example, jhonnyguru reports my PSU +12v rail is outputting 12.5v, yet HWiNFO only shows 12v.

I know there are always some variations from PSU to PSU, but thats a huge variation.

Cheers!