Friendly warning concerning Vega 64 and pcie plugs

[Phixsator]

So i just want to put out a friendly warning/heads up to those of you who are using or considering getting a vega 64 and are using a pcie cable with double 8 pins like there is on the psu i have which is the corsair ax860. Now let me stress the following: I love my vega 64. I wouldn't change it back. However considering i got a quality psu capable of supplying 300w+ over 1 pcie cable i thought 1 would be enough and it wasnt.

Yesterday i started getting black screens whenever i opened a game requiring a complete reset to get picture back. Turned out that at some point one of the connectors in the pcie cable had fried due to too much current which is insane considering that during insane stress tests i havent seen the card draw more than 290w if HWINFO is to be believed. I have since switched to 2 single 8 pin cables and without doing anything else the machine now works fine without issue. Just blows my mind the amount of amps that must have gone through that pin in a spike that makes the plastiq melt like it did.

I would like to also add that the card was running undervolted using the new undervolt feature and has never been overclocked as i really didn't see a point in doing so considering im on a 1080p monitor.

Spoiler: Picture of melted pin

so
TLDR; USE 2 individual pcie cables from the PSU if you don't want 1 to fry!

 

[Rroff]

EDIT: nm

 

[koooowweeee]

Isn't that for the motherboard? I've never seen a 8pin cable before.

Also I've only ever seen a connector melt like that when it's not been pushed in properly

 

[chaparral]

But a single 8-pin PCI-E connector is rated for 150watts (not 300watts)

 

[Thekwango]

But a single 8-pin PCI-E connector is rated for 150watts (not 300watts)

Same. 75w for 6 pin and 150 for 8. Least that’s what it used to be as far as I remember.

 

[Kaapstad]

Same. 75w for 6 pin and 150 for 8. Least that’s what it used to be as far as I remember.

That is at the end that plugs into the card but if two of these are on the same cable it means that the other end has to handle 300w or more as it is possible to draw more than the PCI-E spec.

 

[andy_mk3]

My GTX1080 won't even boot with both plugs off one cable.

 

[Thekwango]

That is at the end that plugs into the card but if two of these are on the same cable it means that the other end has to handle 300w or more as it is possible to draw more than the PCI-E spec.

Sorry, posting from my phone so apologies for my poorly worded post.
My thoughts were by just using one pcie cable you could potential overload it?

 

[Kaapstad]

Sorry, posting from my phone so apologies for my poorly worded post.
My thoughts were by just using one pcie cable you could potential overload it?

AMD have issued guidelines and warnings in the past for use with the 295X2 cards due to overloading PSUs and cables with twin connectors.

I always prefer to play safe and use one cable per connector.

 

[WantoN]

I’ve always used two separate cables for CPUs. I think it’s generally good practice.

 

[Thekwango]

AMD have issued guidelines and warnings in the past for use with the 295X2 cards due to overloading PSUs and cables with twin connectors.

I always prefer to play safe and use one cable per connector.

Same. Always 1 cable per connector. Not sure why the op seems to think it’s ‘new’ news. There’s a myriad of troubleshooting posts on here about gpus and almost all of them 1 of the first questions is - are you using 2 seperate cables.

 

[ltron]

Same. Always 1 cable per connector. Not sure why the op seems to think it’s ‘new’ news. There’s a myriad of troubleshooting posts on here about gpus and almost all of them 1 of the first questions is - are you using 2 seperate cables.

It's a mistake that many of us have made though in the pursuit of neatness. When I had my R9 390X I used only one cable, there were no warnings against doing so in the manuals of either the card or the PSU and I simply assumed that the fact there were two plugs on the cable meant that it could handle it, thankfully no damage was done. Now I know better of course, but the companies that sell the hardware need to do a much better job of informing customers, particularly when they buy power-hungry cards.

 

[Confused Stu]

Isn't that for the motherboard? I've never seen a 8pin cable before.

I was wondering that, as the keying of the connectors (which ones are square) doesn't match PCI-E standards, but then I realised it doesn't match the CPU 12V input either. Finally I twigged, it's a modular power connector and the connector photographed is the bit that pushes into the PSU itself - presumably with 2 x 6+2 PCI-E connectors on the other end of the cable from the rest of the OP's post.

 

[Thekwango]

It's a mistake that many of us have made though in the pursuit of neatness. When I had my R9 390X I used only one cable, there were no warnings against doing so in the manuals of either the card or the PSU and I simply assumed that the fact there were two plugs on the cable meant that it could handle it, thankfully no damage was done. Now I know better of course, but the companies that sell the hardware need to do a much better job of informing customers, particularly when they buy power-hungry cards.

Oh yea without a doubt. I’m surprised PSU’S don’t come with some sort of guidance. Given the litigious world we live in (especially the USA) it’s only a matter of time before someone tries to sue over a fired gpu.

 

[RynceWynd]

I think this is a friendly warning for people to read their PSU documentation. The stickers they put on the side of the PSU that says what the maximum load across each rail is actually means something. if in doubt ask.

 

[Puppetmaster]

I think this is a friendly warning for people to read their PSU documentation. The stickers they put on the side of the PSU that says what the maximum load across each rail is actually means something. if in doubt ask.

So your saying he was drawing over 858W then?

 

[LoadsaMoney]

Ive got the AX860 PSU too, and use 2x seperate cables to power my LC64, had no issues at all, and i havn't undervolted it or nowt.

 

[james.miller]

That didn't happen because you used one cable. I am certain the single cable from the PSU is good for the 300w maximum draw the two 8 pin connectors on the end of if are rated for. No, that kind of localized damage almost always happens as a result of a faulty connection.

 

[Phixsator]

I ran a 1080ti for 1½ years and had it its nuts overclocked to the max i could push it on a MK-26 running only 1 pcie cable from the psu(splitting into 2 8pin pcie) without issue so the only explanation to this is some sort of spike happening for a brief moment as the vega 64 should not pull out of spec power over the pcie cable during normal operations. But it is a good reminder for the future to just play it safe even if it should work on paper.

Im just glad i didn't skimp on the psu when i bought it.

 

[Phixsator]

That didn't happen because you used one cable. I am certain the single cable from the PSU is good for the 300w maximum draw the two 8 pin connectors on the end of if are rated for. No, that kind of localized damage almost always happens as a result of a faulty connection.

That seems odd to me cause the psu have been in the case for years now and that plug have not been touched and was firmly secured in the socket of the psu when i checked the first time.

a quick gpu test in aida64 shows a power draw off around 700 watts on the wall with an idle system draw of 150ish due to disabled power saving features. That is with 20% power limit. The highest i ever saw my 1080ti reach was around 550w completely oced (entire system) and again measured at the wall.

With 0% power limit its staying at roughly 650w at the wall.. jeezes its hungry I guess i got some tweaking to do as i have clearly been a bit ignorant of the actual power draw this thing can ask for.