Question No picture from GPU

[oceiros]

Specs:
Processor: Intel i7-6700K Quad Core 4.0Ghz
Mobo: Msi z270-a pro
GPU: AMD Radeon RX Vega 64
16gb RAM (1 stick)
850W Power Supply

Since I recently bought the above GPU to replace my old msi 1050, I haven't been able to get a picture from it. I've tried CMOS resets, uninstalling old GPU drivers using DDU (although I didn't know I had to do this until after I first tried installing the GPU, not sure if that may have caused permanent damage but I had no issues doing it this way for other GPU installations) , and updating my motherboard's BIOS to the latest version (I'm assuming that support for my GPU wouldn't be restricted to an older version).

At one point I thought I had fixed it- I was using a faulty adapter to try and connect the gpu to my monitor. After going for a direct connection, I got a picture and was able to install the drivers. However, I installed a new CPU fan the next day (didn't check before installing it that things were running fine) and the picture was gone, and I haven't been able to get it back, aside from when I uninstall the GPU and go straight from the mobo's display output.
I think there's something obvious I'm missing, but can't quite put my finger on it.

 

[NightHawkRMX]

Make sure the GPU has the proper power connectors connected.

What is the make and model of power supply

 

[oceiros]

It's an EVGA 850 B3 PSU.
I did read something about daisy chaining being an issue. The PSU comes with 6+2 pin cables to power the GPU, but with two 6+2 pin connectors and an 8 pin I believe on the other end to connect to the PSU. My GPU requires 2 8 pin connectors to power it, so i used one cable to do so, using both connectors. I'm not sure if this was the wrong thing to do, but I also tried it with two seperate cables from the PSU to the GPU, which didn't work either.