Is this 12V fluctuating under stress normal?

[RendoCN23]

I'm asking since I'm a bit scared since a friend told me that this line shoud be stable and flat all the time.

http://i.imgur.com/NXJerW8.jpg

 

[Aeacus]

It's completely normal that PSU +12V rail fluctuates.

According to the ATX PSU standard the fluctuations on +12V rail can be no more than +/- 5%. That means the +12V rail can fluctuate between 11.4V and 12.6V.

Most good quality (Tier two) PSUs have better voltage regulation than required by ATX standard and can maintain 12V regulation of 2% - 3%. Great quality (Tier one) PSUs have even tighter 12V regulation and can maintain 1%.
I happen to have the best 650W PSU money can buy at current date in my Skylake build (full specs in my sig) and my PSU, Seasonic PRIME 650 has extremely tight voltage regulation, achieving regulation under 0.5%.

PSU Tier list: http://www.tomshardware.co.uk/forum/id-2547993/psu-tier-list.html
And further reading about best PSUs at current date in almost every wattage range: http://www.tomshardware.com/reviews/best-psus,4229.html

 

[Endre555]

It looks like normal to me. The voltage of the +12V mostly fluctuates accordingly to the load the PC puts onto it.