Are PCI-E slots powered by a single cable out of 24-pin connector?

[AdmiralMyxtaR]

I have seen signs of heat damage on a single cable in 24-pin connector (№11 on the layout, neighbouring №10, which is 12 V as well is fine)  on both power supplies that I connected to my dual-GPU rig. I've read somewhere on the Internet that 2 cables can manage up to 192 W, so one of them is 96 W, and 2 GPUs can draw up to 150 W through it, and then heat damage signs are not reasonless. But if that's the case, should you take repercussions when using dual-GPU for extensive periods of time? PSUs shut down, tripping some kind of protection and connector is super hot to the touch. Have I just trashed both my power supplies? They were both more than enough to handle the GPUs.

[Jurrunio]

If these are RX 480s (famous for breaking the 75w through PCIe slot limit) then I'm not surprised, but no the PCIe slots recieve power from 2 wires in the 24pin ATX connector. something could be wrong with your motherboard

[AdmiralMyxtaR]

1 hour ago, Jurrunio said:

If these are RX 480s (famous for breaking the 75w through PCIe slot limit) then I'm not surprised, but no the PCIe slots recieve power from 2 wires in the 24pin ATX connector. something could be wrong with your motherboard

How can I check if it's motherboard? I don't have any spare mobo's capable of housing 2 GPUs

[Jurrunio]

1 minute ago, AdmiralMyxtaR said:

How can I check if it's motherboard? I don't have any spare mobo's capable of housing 2 GPUs

what power supply are these?

[AdmiralMyxtaR]

Just now, Jurrunio said:

what power supply are these?

1) EVGA SuperNova G2L 750 W (don't have it for now since I thought it was the issue and it's now on RMA)

2) Cougar PowerX 700 (around 4.5 years old, worked fine till today, exact same shutdown behavior like with 1), but since cables are colored the damaged cable is blackened closer to the motherboad connector. It's neighbour is completely fine)

 

[manikyath]

1 hour ago, Jurrunio said:

If these are RX 480s (famous for breaking the 75w through PCIe slot limit) then I'm not surprised, but no the PCIe slots recieve power from 2 wires in the 24pin ATX connector. something could be wrong with your motherboard

to be honest, for a decent power supply (or rather one with decent cables) 75W is still a fairly "safe" estimate.

 

on topic: the power draw from pcie slot thing is a bit of a vague market, because technically every slot on your board is rated for up to 75W, but especially on the more "basic" side, mobo spec sheets ofen make it seem like the 75 watt limit is shared between all slots.

The RX480 does indeed treat that 75W limit a bit too lightly, but from what i recall AMD released a patch that would bias the power consumption towards the 6-pin, essentially solving the issue. and either way, it still shouldnt draw such significant load that your 24-pin cables are burning out. this seems more like a fault in your motherboard, or a combination of more factors than just the GPUs.

[Lord Nicoll]

I've done a fair bit of overclocking GPU's while pushing volts and disabling power limits. The limit of a board really depends on the board, the connector quality on both the PSU and mobo side, the amount of copper in the board, and how much power is actually taken by the slots. While pushing two GTX 480's, that was the only time I noticed power usage through the board. I tested it again on heavily overclocked cards and found a lot often pulled over 100 watts total. What's the motherboard?

[AdmiralMyxtaR]

6 minutes ago, Lord Nicoll said:

I've done a fair bit of overclocking GPU's while pushing volts and disabling power limits. The limit of a board really depends on the board, the connector quality on both the PSU and mobo side, the amount of copper in the board, and how much power is actually taken by the slots. While pushing two GTX 480's, that was the only time I noticed power usage through the board. I tested it again on heavily overclocked cards and found a lot often pulled over 100 watts total. What's the motherboard?

Gigabyte 970A-UD3P rev. 1.0

[Lord Nicoll]

43 minutes ago, AdmiralMyxtaR said:

Gigabyte 970A-UD3P rev. 1.0

Well it's not the highest end board there is, and the AM3+ platform is pretty outdated as is. I don't know how good the internal 12v plain is on that board. If you're worried about supplying enough enough power to the cards, you could get a new board that has additional supplemental power for the slots, but I wouldn't recommend buying an AM3+ board now, which would make that a waste of a purchase. How bad is the damaging to the cable insulation? I'd say just wait a bit and upgrade to either coffee lake or Ryzen, you'd see a decent improvement in gaming if that's what you're using the cards for.