So, my PSU just melted

iviv · 19 May 2020 at 01:14

Specs: Seasonic focus plus gold 1000w psu
Powercolor red devil vega 64
Amd 3900x
Gigabyte X570 Aorus Pro

I had been dealing with some stability issues for the last couple of months and had been trying to rule various components out, switching out almsot everything while struggling to pinpoint the actual issue, but never actually touching the PSU since it never occured to me that it could be the problem. Long story short, yesterday I suddenly experienced a ton of graphical corruption and then the PC switched off, and I could smell a burning plastic smell. Looked into my pc case and (images spoilered due to size):

The cable from PSU to GPU was hot to the touch, had melted off the insulation at the PSU end of the cable, and had also melted some pins from the connector, requiring some serious tugging to separate.
Thankfully I had recently ordered a psu for a NAS and I've been able to swap that in to keep my main rig going in the meantime.

Doing some googling, I found this article from guru3d which notes that units with serial numbers from before Jan 18 could shutdown under heavy load. This matches up with what had been happening over the last few months, though I've not been able to find a way to tell the production date from the serial number.

OcUK directed me to Seasonic for RMA due to it being purchased over a year ago (Aug 18), and Seasonic were quick to approve the RMA and send a shipping label, but I noticed that I have to cover the cost of shipping it back to them.

So, I've got a couple of followup questions from what happened. Firstly, is it normal for the customer to pay the shipping cost to them? I wouldn't mind so much if it was the case of paying to ship it to them, and Seasonic then refunding the shipping cost if the unit was indeed faulty, but when a power supply literally melts, I feel a little miffed that I'm ending up out of pocket as a result. I've not prepared a box to ship it in yet, since I don't have the original packing to hand, but given the weight, I'm imagining it won't be too cheap to ship.

Secondly, I'm a little concerned about the rest of my system. From some testing and benchmarking with this backup psu, everything does appear fine. The main component I would be worried about is the graphics card since it was the GPU cable that melted. As mentioned, it appears to benchmark ok, so I'm assuming nothing is wrong, but I'm a little concerned that down the line if it starts playing up, could it have been caused by the PSU dying like this? Or would the various protections built in to it have caught any danger and limited the damage just to the PSU itself?

Thanks for your time and happy to answer any followup questions.

iviv · 19 May 2020 at 08:46

It's going to Milton Keynes. Their RMA email notes:
IMPORTANT! The sender is responsible for the delivery of the package including the costs of shipping. Please select a shipping method with tracking information. Seasonic cannot be held responsible for lost or damaged packages. Learn more about Seasonic RMA policy.

iviv · 19 May 2020 at 15:02

pastymuncher said:
Were you powering the gpu from a single lead, as in both daisy chained connectors on a single lead? If so then that is most likely what has caused this. Vega and especially Vega 64 has stability problems when powered by a single lead from previous threads I have seen on here and all were cured by powering the card with two seperate leads. What it looks like has happened is that due to being powered by a single lead the gpu has tried pulling too much power for the lead which led to it heating up and melting the insulation and plug. Always use two seperate leads when powering a power hungry card.

Yes, outside the first year the sender is responsible for postage costs and it's quite normal. Some companies such as Gigabyte charge you for the return postage. Inside the first year we should always go through the place it was purchased from and should get postage fee's refunded.

Yeah, I'd come to that conclusion myself. For cable management I'd just gone with the single cable on the assumption that a) the cable would be able to meet the ATX spec on both 8-pins at the same time and b) the gpu wouldn't pull more than the ATX spec over each 8-pin. Not sure which of those assumptions was incorrect (Or why it took 18 months for this to happen), but I'll definitely be using separate cables with the replacement psu.

iviv · 19 May 2020 at 19:31

mattyfez said:
I didn't reply earlier but I had the same thoughts.

A) It stands to reason that if a high power PSU has 2x PCI power connectors on 1 cable, the plug and cable gauge should be able to cope...
B) It also stands to reason that if you have a GPU with 2 PCI power sockets you should use 2 separate physical cables where possible to spread the load, but that's not really specified from what I can see, the fact you can have 2 full on GPU connectors on one cable is worrying unless the cable gauge is pretty thick, and that could be a crucial issue as demonstrated in the pic above.
C) I wonder if graphics cards at the meatier end of the market exceed ATX spec, or if it's even specified in ATX spec? without downloading ATX spec documents, I'd hazard cable gauges and plug are not.

or
D) the cable/plug could simply be defective/freak accident.

Either way, your lucky that didn't turn into a house fire!!

Yeah, like, if it was an 8 and a 6 pin on one cable then sure, I would use two of the cables and the 8 pin from each, rather than doing something stupid with the 6 pin and an adapter to turn it into an 8 pin. If you're putting two 8 pins on the same cable, using a reputable branded high power PSU, then I would expect that it should be able to power them.

THW's review of the gpu shows an absolute stock peak of 364W power draw, a smidge under the combined 2x8 pin + pci-e slot 375W supply. The peak OC mode apparently hit 400W, though I was running the card stock without any extra OC or power boosting.

Seconding the comments about being glad I'm not on fire though. Started looking around my flat and realising I'm not entirely sure what I would have done to try and put it out. Maybe just unplug it at the wall, pull cables from the back and drag the case out to the fire escape as long as the flames weren't too bad. Maybe I should grab a small fire extinguisher or blanket.