PSU and GPU blew my house fuse?!

Posted by s22sk123@reddit | buildapc | View on Reddit | 24 comments

Just upgraded from a 3060 to a 5070 using a new 850W PSU (with 12VHPWR adapter, 2 separate PCIe cables).

Initial install: PC booted, GPU worked fine.

Shut it down, unplugged to double-check connections.

When I plugged the PSU back in, I heard a pop and it instantly tripped my house fuse/breaker(idk what its called)

After that:

PSU trips breaker even when tested alone

There’s a burning smell from the PSU.

Found a loose screw on the motherboard (not sure if related)

I put my old PSU + old GPU back in:

PC boots fine

Had to fix Windows bootloader, but system works

So now I’m wondering:

Did the PSU just fail on its own?

Could the loose screw have caused this?

Any chance the new GPU got damaged?

Would appreciate any thoughts before I plug the 5070 in again with a replacement PSU.

[-]

Over_Fix_7890@reddit

Change the power supply, also what is the full name of that power supply?

[-]

s22sk123@reddit (OP)

Seasonic CORE BC-850 toiteplokk, 80 PLUS Bronze, ATX 3.1, PCIe 5.1, 850W

[-]

s22sk123@reddit (OP)

I bought a semi modular gold, will assemble in an hr 🫣

[-]

dertechie@reddit

Time to see if it’s a known bomb or of it’s the reason we speak of the bathtub curve.

[-]

aCarstairs@reddit

I gotta ask but you made sure to replace all psu cables right? So no cables from the old PSU were used with the new PSU?

[-]

aCarstairs@reddit

Fantastic. Always a good one to make sure

[-]

aCuria@reddit

There’s a burning smell from the PSU.

Return it.

[-]

dnichll@reddit

he said it was on the motherboard, so definitely possibility of shorting something power delivery related.

[-]

s22sk123@reddit (OP)

It was stuck like stuck under an m2 drive, so yes, on the motherbord. I also assembled the back with my old psu and gpu, its working fine

[-]

dnichll@reddit

i think thats the most likely culprit. iirc, a good psu will blow themselves up to protect other components in overcurrent or overvoltage events.

[-]

aCuria@reddit

I’m surprised the motherboard isn’t dead if that’s the case

[-]

s22sk123@reddit (OP)

Mobo seems to work fine. What would you suggest me do? Get a replacement psu and everything else should be fine?

[-]

aCuria@reddit

Replace the psu and give it another go

[-]

even lower tier psus from recognized brands have these protections built in to protect components. how well theyre implemented are up for debate but damage to components from these events are usually the exception not the rule.

[-]

aminy23@reddit

a new 850W PSU (with 12VHPWR adapter, 2 separate PCIe cables

In 2004-2007 the ATX 2 standard was made and finalized. In 2023-2025 the ATX 3 standard was made and finalized with 3.1 being the final version.

If this is indeed a new PSU - then it should be made to the ATX 3.1 standard where it should have a 12V-2x6 cable that can plug directly into the GPU.

If the PSU isn't ATX 3+, then it's essentially possibly anything from the last 20+ years.

But yes - if the PSU is smoking and tripping circuit breakers - then it's likely something short circuited causing excessive current to go through tripping that breaker. That excess current has nowhere to go to so it ends up as heat smoldering something.

Take the PSU out of the PC and jump it to see if trips the breaker. If it does - it's toast. Shake it to see if a screw falls out - thats's probably your fault. If it doesn't - the PSU is probably a dud and should be returned/RMA'd.

[-]

s22sk123@reddit (OP)

The psu also tripped without anything connected to it, ofc i tested it after the first time.

Additionally, it did have 2x6 labeled 600w connector, but the gpu had a adapater with it in the box and it advised to use that one, so i did.

[-]

aminy23@reddit

The one from the PSU is usually safer now if it's 12V-2x6 and not 12VHPWR. The absolute safest is new ones with colored tips - for SeaSonic I think it's Blue.

The ATX 3.1 PSUs are able to talk with the GPU to detect issues. Using the adapter bypasses that safety feature.

[-]

s22sk123@reddit (OP)

I will keep it in mind after i get a replacement