Anyone powered his S7 using only 1 PCi-E 6 per board ?
I have powered them with only 1 cable per board for the last 2 days and they were working fine
Just today I read somewhere that it actually needs all 3 cables per board.
That's over 350W DC for 1 cable. The connectors/pins are only rated for a maxijum of 324W, and those ratings aren't overly conservative given the demanding environments mining puts on them (vibration + high ambient temps). Plug more cables into them, like now...
Edit: Plus it violates Bitmain's ridiculous warranty terms...
I'm doing 8 total, 2 each to outside boards and 3 to center plus controller. That way I can use 2 dell 750 PSU with 8 cables. Using high quality 16awg cables and breakout boards. No issues. Been monitoring temps of connectors and cables. Avg connect temp is 79F. Miner runs at 55-59c and ambient temp is 69-72F.
That would be 175w per cable on the boards with 2 plugged in. Consumer PSU may not handle this since cables are lower gauge and will heat up more.
The wire gauge on the bitmain 1600 psu's is pretty teenie.
Maybe that is why the "three cable rule" is pushed.
My corsair rm1000 modular cables are pretty beefy. I use two per board with the daisy chain from one of them, filling all connectors.
The board next to the controller socket gets the daisy chain from the second cable.
I'm not sure what the wire gauge number is on the Bitmain power supplies, someone will have to see if there is some printing on the wires and post the AWG size.
BUT, for reference, when I made the cables for the DPS-1200FB power supplies I have, I used 20ga wire.... its what I had laying around that would fit the pins I have.... Calculating the load per wire, I divided the maximum amperage the power supply could produce across the 6 Molex plugs, the amperage per pin/wire was 5.5 amp.... WELL within the specification for the wire size and insulation type using an NEC wire chart.
YES, insulation type is also a factor. You can have anything from varnish coated wires, plastic insulated, silicone insulated, or even teflon insulated. Some insulation melts at lower temps, so if you have a Molex connector that heating up because of old age or you have been plugging and unplugging a lot and you have cheap ass plastic insulated wires, more likely you will have a meltdown from insulation melting then wires shorting out than if you were running a smaller wire gauge, same amperage, and teflon insulation.
You might think silicone insulated wires will handle the heat... somewhat. Silicone insulation is used when maximum flexability is required, or is in a higher heat environment, or is carrying higher voltage (think 1000V or more). Silicone insulation is not very good when its in direct contact with a high temperature material such as a wire which has a contact that is micro arcing causing the wire to heat up massively.... it will melt with relative ease.
As far as pluging and unplugging, I use the corsair rm1000 1000 watt psu with modular connectors.
I plug the modular cables into the s7 once and LEAVE THEM THERE. Two pcie cables per board with one daisy chain connector per board.
When I need to detach the psu from the s7 I unplug from the psu only.
This way the s7 power connectors stay more pristine.
Again, the gauge on the bitmain 1600 watt psu is quite small so use all connectors on the s7.
