Problem with MVIII Ranger Z170 major PCI-e slot

[liyihaha]

Hello,
I build a new system recently and was bothered by a problem for ~2 weeks. The config is:
CPU: i7-6700k (stock freq, no oc)
Cooler: Corsair H90
MB: ROG MVIII ranger
RAM: G.Skill 2*8GB DDR4-3000
Video card: EVGA GTX970 SSC w/ACX2.0+
500G Samsung 850 evo SSD + old Seagate 1.5T 7200rpm HDD
PSU: Corsair RM850 850W (returned), EVGA supernova 850 G2 850W (current)

My computer will shut down when the GPU is on load. It usually happens when I do gaming or 3d mark 11. It just shut down the power and no erro code or warning about overheating. I have done a lot of diagnostic and test on this.
Firstly, I checked for potential overheating problem. I ran some stress test on CPU and RAM use Prime95 or intel CPU diagnostic tool. It passed every test without any problem. The CPU did get warm but my Corsair H90 cooler did the job and no overheating warning observed. The highest temp was read as 70C from HWmonitor.
Then I checked the video card, I put my video card into another z97 system and ran the same test (3d mark 11 or games) and no problem at all. The highest temp was read as 78C.
So I start to suspect the PSU so I test 2 more PSUs and returned my first RM850. But it did not solve the problem.
Then I have to start looking at my MB. I updated the bios to the latest version. It gets a little bit better. I found a trend that the problem will be more likely to happen if I use a more aggressive fan profile. If I ran the test under default fan profile (no EVGA precision X app), it can survive 2 consecutive test without shutting down even GPU will heat up to 78C.
Finally I found if I put my video card into slot 2 instead of the major pci-e slot, it can eliminate all the problem when I ran the test. I will do one more repeat tomorrow. But I feel it may indicate my major pci-e slot has some problem during high wattage loads. I don't know if anybody have similar problem before? I always trust ASUS product so I just want to see if it is really a hardware problem. If it is, I will initiate a refund since I bought it 2 weeks ago. Or there might be some conflict and it may can be solved by doing some software work?

[Chino]

Can you list the exact model of your memory kit for me? Also does this happen with your system at stock with RAM at 2133MHz?

[liyihaha]

Chino wrote:
Can you list the exact model of your memory kit for me? Also does this happen with your system at stock with RAM at 2133MHz?

It is G.Skill F4-3000C15D-16GVR. I am running it at stock speed 2133MHz. I did not overclock anything.

[Chino]

Can you confirm that you've populated the 8 pin power header on the motherboard?

[liyihaha]

Chino wrote:
Can you confirm that you've populated the 8 pin power header on the motherboard?

8 Pin power header? You mean the 8 pin power header for CPU or GPU? I did check all the power pin and make sure they were plugged in properly. I also repeated the video card switch experiment and got same results. It will shut down the computer when I put my card into slot 1. But it is find on slot 2.

[Chino]

I'm referring to this header.

[liyihaha]

Chino wrote:
I'm referring to this header.

I am pretty sure this was plugged in properly. I still ran some CPU stress test with Prime 95 and there are no problems at all.

[Chino]

I notice that your EVGA GTX970 SSC w/ACX2.0+ uses a 8 pin PCIe cable and a 6 pin PCIe cable. Are you using one single PCIe cable to power both connectors? Or are you using two separate PCIe cables to do so? If you're using one cable, please try using two cables for testing.

Since your EVGA supernova 850 G2 850W PSU has a modular design, try alternating between the different VGA connectors to see if that makes a difference.

[liyihaha]

Chino wrote:
I notice that your EVGA GTX970 SSC w/ACX2.0+ uses a 8 pin PCIe cable and a 6 pin PCIe cable. Are you using one single PCIe cable to power both connectors? Or are you using two separate PCIe cables to do so? If you're using one cable, please try using two cables for testing.

Since your EVGA supernova 850 G2 850W PSU has a modular design, try alternating between the different VGA connectors to see if that makes a difference.

Thanks for your suggestions. I did try them previously and no improvement.

Now I am pretty sure it is due to my Ranger MB since I bought a new ROG MVIII hero. No problem at all. I have test it from for the whole weekend and it ran very good. It seems that the major PCI-E on the Ranger MB is somewhat defective when it is running on high wattage and it cuts power when GPU is on load.