Seeking help on Asus Z270A MB shorting issue

[webferrett]

Hello all,

 First post and I want to thank this group for all of the great advice and suggestions posted throughout this board as I have learned alot from reading through these forums.

 My question: I have shorted out 3 Asus Z270a MB in the last 2 days setting up another rig. I think I may have narrowed it down to cause but would love some input from this group.

Setup:

8 Nitro Sapphire 8g Special edition.
4g  ddr 2400
G4400 cpu
variety of different risers.
2 Corsair 850 HX series PSUs.
scan disk ssd
Explomos m2/ pci adapters

I tested each board before mounting. Had power lights and rgb lighting. After mounting connected everything but the Gpu's/Risers. I was able to load the OS on all 3 boards and they functioned properly. Completely powered off device and removed power to draw all power off board before attaching my first GPU. As soon as I powered on, the board powered up and then went dead. Was never able to power on again. After removing all devices and trying all other options I noticed PCI # 5 was getting hot and starting to smell. I assumed bad board. Ordered 2 more and going through the same process outlined, got exactly the same result using 2 different Gpu's connecting to 2 different PCIe slots. I am powering the risers with molex/sata adapters. I have seen others post in regards to this but I have other rigs running this setup and no issues.

I have another rig setup using all of the same items I have listed above but the PSU's. That rig is using 2 EVGA supernova 850's. I had no issues at all with that rig and it runs great. This PSU has 8 pin to 8 pin + 6 Pin. I used both power connections on the Sapphire cards and they run great. Card has 8 pin and 6 pin power connectors.

However. The current build PSU's (Corsairs) have 8 pin to 2(6+2 pin). I wanted to setup using both power connections on the card so I did the 8 pin and 6 pin leaving the 2 pin open.  I would have thought this would have been ok but I am now starting to think that is not the case. Possibly an incorrect voltage? I unfortunately don't have anymore boards to test that with just only the 8 pin connection.

Any advice you could offer would be greatly appreciated.
Thank You

Wade

[Nexillus]

What are the PSU/PSU's you connecting to the MB's that have been fried?

[webferrett]

2 Corsair HX 850. No issues booting MB/Scan disk ssd/memory/G4400 cpu and loading/configuring Win 10. All 3 boards worked normally and I was able to configure MB and win 10 with multiple reboots on all boards. It was when I started attaching GPS's to configure. I do one GPU at a time. I have another rig using the corsairs and they are fine using Nvidia. I have another rig same setup as I am configuring now running great but on Evga Supernova 850's. The only thing I can lean to is the power to the cards with the 2x(6+2) leaving the 2 open for the 6 pin GPU connector. It has to be something with Voltage as I cant see the risers shorting the board. They would either allow card detection or not.

Thank you,
Wade