Topic: 6 GPUs on MSI X399 SLI Plus (Read 147 times)

Hello,

last week i started building my first rig, it was slowly growing, since not all parts arrived the same day. Up until 4 GPUs everything went fine. Installed HiveOS, it always found the new card and started mining. Today I tried to connect all 6 GTX 1060s, at first it didnt boot at all. After many hours of switching riser, enabling/disabling stuff in BIOS, the best it could manage was: All 6 cards working + CPU mining for about 1 minute, after that one GPU stopped mining and after a few minutes another one stopped.
Currently it is running stable with 5 cards and CPU mining disabled.
I dont think that the card/riser are broken, since i can switch them and everything still works. The problems occur, when certain combinations are present, i.e if I put a card into PCIe 3 and 1 (PCIe 3 is the slot making the most trouble).

The system:
OS: HiveOS
CPU: Ryzen 1950X Threadripper
PSU: LC1000 v2.4 (1000 Watt)
RAM: G.Skill TridentZ 32GB
MB: MSI x399 SLI Plus
GPUs: 3x 6GB Palit GeForce GTX 1060 DUAL
2x 6GB Gainward GeForce GTX 1060 Phoenix
1x 6GB Asus GeForce GTX 1060 Dual OC
All riser are powered by SATA with max 2x riser/cable.

The moment the system worked with 6 GPUs it drained ~840Watt from the wall, so I dont think it is the PSUs fault. If I only use 1 GPU all PCIe slot can be used, 2 GPUs, too, but from 3+ i need to test for working combinations as I discovered todey.
Any idea what to check next?