I have two Corsair CS850M which are gold rated. One is powering two GPUs and the CPU, the mobo power is split between both and the second GPU is powering two GPUs. All are 1080Ti.
The cable that came with the PSU for the GPU power was 8 pin one end and two 6+2 at the other end. At present I have the 8 pin plugged into the PSU and the two 6+2’ at the other end plugged into the two 8 pin inputs on the 1080Ti.
It works, but I have to limit the power to the GPUs to 190w each in Simple Mining OS, any higher and the cards crash. I read that 8 pin can carry at least 150w, but not sufficient to give full power to the card. If I disconnect one GPU and set the second to 225w, it still crashes, so I am thinking it must be a power limit somewhere.
I read that its better to power the second 8 pin input on the GPU with a separate cable direct to PSU, a second 8 pin would give another 150w, but I’d be fine with another 75w as I’m not bothered about overclocking, its more that I want stability and not rebooting several times a day due to cards crashing.
As I don’t have any more 8 pin outputs spare on the PSUs but do have some spare 6 pins, I was thinking to run a 6 pin with a converter to 8 pin and that would give an extra 75w whilst populating the two 8 pin inputs on the GPUs as they need to have 8 pins plugged in to work. I would of course get cables suitable for my PSU, i.e. Corsair.
I also note my risers are currently powered via SATA to 6 pin adapters which I am about to change to 6 pin to double 6 pin (one for each pair of risers) as I understand that is ample power and using the SATA adapter is a fire risk. I also wondered if the issue could be insufficient power going to the risers.
Hope this clarifies.