230v, Europe here, but yes. There's literally only mobo, cpu, cpu cooler, 1 ram stick and hdd connected (happened even without the HDD). I mean, I'm grateful for your responses, but I (mostly) know what I'm doing.
What I'm asking for is that, based on the video of the voltage drop, whether one can tell if it's def. the PSU or is it possible (not certain, but _possible_) that the mobo is the one causing trouble.