Msi X470 ram issues

[Caolan.Kelly]

My brother upgrade his rig to a ryzen 5 2600 and msi x470 gaming plus. He also got a kit of corsair vengence lpx ddr4 3000 mhz ram. 

Ever since the upgrade the ram will only work using dual channel and only in slots 3 and 4. If placed in any other slots say 1 and 3, or 2 and 4, or 1 and 2 it will only begin to but up and fail. after looking around here i found that hes not the only one with this problem and was wondering if anyone had any solutions. I should also mention he had to increase the voltage to the ram to initially get the system to boot properly as he was only getting 8gb, and the other 8gb was reserved.  after increasing the voltage we could get it to run at 2993 and the 16gb but it still seamed strange to that it would only work in slots 3 and 4. 

 

Thanks for any help