So for the paperclip test you disconnected everything, right? Otherwise it doesn't work.

It really sounds like overheating.

Afaik the Nox Urano VX 650W is a 400W PSU sold as 650W because fuck the customers. It's terrible.

Yep, I disconnected all the cables and stuff before doing the test.

I'll try to keep monitoring the temperatures to see if anything unusual happens. I was thinking of maybe changing the case and / or the coolers, but my budget is pretty tight right now.

And about the NOX Urano... should I get a refund? I mainly picked that one because all the reviews said that it was a pretty good PSU for its price, but there was no mention to that 400W shit.

99% sure it's the PSU overheating then.
I mean if the PSU doesn't start with nothing connected to it, what else could it be?

Yes, get a refund. Which reviews?

Mostly the customer reviews of the store page, but also other external reviews and videos. They were all very positive and I didn't found anything about the 400W, but now I'm worried.

If I refund it, which one should I buy?

Well customer reviews are not useful in that regard since they wouldn't be able to figure it out.
Links to the "external reviews" and videos?

It would probably best to link me the shop you'll be buying from. There's lots of options, but it depends on the price and availability.

I checked this and this review, and also other couple of videos on youtube.

Also, I usually buy all this kind of stuff on pccomponentes.com.

See, the problem is the only tested with 300-350W, that's not really how you should test a "650W" PSU.
Notice how in the first test the +12V voltage dropped 3% going from idle to load, probably <300W difference. What do you think would happen with the full 650W load? Hint: only 5% are allowed. I don't think that PSU would pass.

The other thing is it doesn't pass 80 Plus. 80 Plus has been a thing for 12 years, 80 Plus Bronze for 9. If a PSU can't pass a 9 year old standard it has to be pretty bad.

I'd try this one.
https://www.pccomponentes.com/seasonic-s12ii-430w-80-plus-bronze

So, they finally accepted my refund and delivered the seasonic one. The first couple of days were good, no problems at all, but it's starting to crash again. Just in case, I double checked all the cables and connectors but everything seems fine and in its place.

It's worth mentioning that yesterday it turned off by itself 3 - 4 minutes after booting it up. Is it enough time for it to overheat? Also, I took the graphics card out and boot the computer with just the CPU integrated graphics but it crashed anyway. I would do the same with the HDD but right now I don't have any (my father throw the old ones in the trash because they were just "useless old junk"... oh welp ¯\_(ツ)_/¯)

I'm lost at this point tbh.

Ok, weird shit is happening.
I'm assuming you did the paperclip test correctly, so if the PSU indeed didn't turn on on it's own the it was definitely not ok.

But other things might be broken as well.
Since you already tried it with the iGPU I can only see 3 possibilities:
1. Mobo.
2. CPU.
3. Software (most likely windows).

Without a different mobo or CPU you can't check that, you could only try what happens on a fresh install or with a bootable Linux on a USB stick.

Alright so I disconnected the PSU and SATA cables from the disk and tried Ubuntu on a flash drive, letting it running while I was doing other stuff, but checking it from time to time to see if it was still working.

When I checked it minutes ago the PC was off, worked for about 4 hours straight. I tried to turn it on but I couldn't even get to the BIOS screen without the computer crashing again; so guess we can discard software or disk problems.

I bet on Setsul saying it's the motherboard.

#40
Just in case the PSU is still overheating (it really shouldn't, but if it's a really badly ventilated case + Spain...) do the paperclip test with nothing connected to the PSU again. If the PSU's fan starts spinning (might stop after a while or slow down) then you can be sure it's either CPU or mobo.
I'm guessing you're not getting any beep codes, so it is rather likely to be the mobo.

#41
Correct, chances are like 90%, but I've had one case where it was the CPU.

Setsul, are you familiar with motherboard capacitor/mosFET problems?

Sort of, but it's not the kind of problem that can be effectively diagnosed over the internet.
Love me some rework though.

Welp... kinda weird to say this, but apparently the problem is fixed now. Dunno how or why, but I didn't get any more crashes in the past 10 days. I didn't change any of the software or hardware either.

I'm really confused, but also relieved. So, thanks to everyone that helped posting here and specially to Setsul :3

Well let's hope it stays fixed.