Hey man

I've got a 6 card rig.

I had a bit of a nightmare getting it all running but after a bit of research I finally got it figured out.

I use a Biostar tb250 btc pro motherboard
6 x sapphire rx vega 64's
2 x 120gb ssd drives
6 x pcie risers
corsair hx1200 & hx1000 PSU's
8gb corsair Ram
G4400 CPU (as it has igfx)

To get everything to work stable I had to do the following;

1. setup the rig without the vega's in it
2. install windows & reboot
3. install motherboard drivers & reboot
4. set my bios to use igfx as primary display drivers & reboot
5. set virtual memory to 110gb (basically use 1 ssd as vram) & reboot
6. connect all vega cards
7. Install blockchain drivers & reboot
8. configure my overclocking / undervolting
9. setup the miner
10. mine

I found that when I used less that 16gb of virtual memory for each card in the rig it would mine for a few hours and then freeze, after some looking around I found a few guys who told me about the 16gb per card virtual memory setting and it's run stable ever since.

Hop this helps man