I have done that but still i get the same error when i add more than 3 GPUs, it say no keyboard detected then it ask's me to enter my dvd an repair windows. 

It says legacy, Do i need to reinstall it in UEFI mode?

Have you installed Windows in UEFI mode with GPT bootsector? If not erase the disk and reinstall drivers.
not really sure how to do that, but ill google it and try 


Have you tried different version of risers?  My latest batch of 006c risers have really crappy USB 3.0 cables and only work in some PCIE slots.
I've just build 4 MSI B250 PC mate rigs and all 4 only worked with 3 video cards. Two center PCIE slots needed older risers.

I have ordered new risers will try them once they arrive.


Thank you

Greetings,

I'm running into trouble while building a rig with this config :
- ASUS H270 Plus
- 1x nitro+ rx 470 8gb
- 3x amd radeon rx470 4gb
- 2x MSI radeon rx470 8gb
- 1200W corsair power supply
- 4gb DDR4 ram
-windows 10 pro *64

I have setup the PC installed 1st then 2nd then 3rd GPU no problem everything was running fine. Then when I tried to plug the 4th GPU onward my pc get stuck after BIOS screen (black screen with blinking cursor top left corner) after few seconds the PC restarts and keeps doing the same. Some times i get warning saying that no keyboard is detected. I have tried changing PCI slots, changing the risers, plug different GPU its always the same 3 runs with no problem once the 4th plugged the problem happens.
I have already updated the motherboard BIOS, enabled 4g decoding, tried to increase the ram to 8GB still the same.

Any ideas?

Thank you