Asus PRIME X399-A Motherboard 8pin PSU

[amintegrate]

I just build a PC with this Asus PRIME X399-A Motherboard and a AMD threadripper 1900x CPU and an RTX 2080 Graphics card.
the motherboard has 3 inlets for power . one normal. one 8 pin and one 4 pin. in the manual it says all 3 should be pluged in from PSU . but when all are in the system won't boot up.
After many trial and error I realized that when I unplug the 8pin power connector it starts running. but at startup page beofre bios it says it is recommended to connect the 8 pin.

now the quesition is should I ingnore this 8pin connector? where is the problem coming from can it be my PSU? it is 700w PSU. or the motherboard has the problem?
I also flashback the bios. as I tried a lot to boot it up and at the end I realized this 8 pin was the problem.

I haven't overclocked the computer though.

can anyone hlep?

Regards

 

[Lutfij]

Make sure you're on the latest BIOS update. I'd ask you to breadboard the system and see if it powers up with all EPS connectors hooked up. According to your manual, you can do with only the 8pin EPS cable and leave the 4pin EPS unplugged and there is also a warning about connecting only the 4pin PES as stated on page 2-7. This is a troubleshooting thread and you should include your specs like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:

 

[amintegrate]

Make sure you're on the latest BIOS update. I'd ask you to breadboard the system and see if it powers up with all EPS connectors hooked up. According to your manual, you can do with only the 8pin EPS cable and leave the 4pin EPS unplugged and there is also a warning about connecting only the 4pin PES as stated on page 2-7. This is a troubleshooting thread and you should include your specs like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:

 

[amintegrate]

the bios is Updated. I have 2x 4pin connectors. can I use these to for 8pin ?
also my 8 pin connectors are 6 pin +2pin which can slide off. my PSU down't have an actual 8pin connector.

 

[amintegrate]

CPU: AMD threadripper 1900X
Motherboard: Asus PRIME X399-A Motherboard
Ram: HyperX Predator 32GB (4x 8GB) 3600MHz DDR4 RAM
SSD/HDD: SSD 500GB
GPU: MSI GeForce RTX 2080 Ventus 8GB Graphics Card
PSU: Kolink Core Series 700W 80+ PSU
Chassis: Game Max Vega Full Tower Gaming Case - Black
OS: windows 10

 

[Dragos Manea]

6+2 pin connector is only for videocards, for motherboard you use 4+4 pins only or 8 pins single unit (not 6+2). So if you ahve more 4 pins conector you can use all of them (4+4 for the 8 one)