i've serched google a bit but the most given answer is to enable 4G encoding in the bios, which i have done, unfortunately it did nothing.
i've tested all risers, the power and the GPUS, they are all working...
OS Windows 10.
Bios version;
aptio 2017 american megatrend, core version = 4,6,5,4
10 dollar to the one who can fix this problem ! (BTC)
This is usaully happens because of the vibration on the rig while it running. Please plug out the USB cable with the PCIe line from the motherboard. If you run with the air conditioned room you will find the dust more on the complete mobo and your graphic card slot.
If you have blower or vacuum cleaner with you. Please use that to clean it and plug it. I am 100 percent sure your all the cards will be detected.
This was technic I do most of the time when I get the issue.