[SOLVED] RAM only working on one channel

[Obviouslyray]

I finally got my last couple parts for my new build in March. Nothing booted, but the ambient lighting on mobo would turn on. I contacted ASUS and was told my mobo was bad. Cool. Well I finally got my mobo back, started testing everything boots. At least to the bios menu.

I'm about ready to put everything into the case and decide to put all my RAM in and test it. 4 RAM sticks stalls the boot at the dram level and no video. Take out a1 and b1, same problem. Took out bios chip and unplugged psu. Same problem. Single stick - b1 or b2 ONLY- works fine.

I'm running hyperx predators ddr4-3200 8x4
I7-9700k
Rog strix z370-f

Any help is sincerely appreciated!

Edit: have now also tried b2+a1. No luck. B1 + B2 seems to work fine, just my A slots. Any thoughts?

 

[RealBeast]

Is this a matched kit of 4 sticks? And what is the full model number on those memory sticks?
Do all groups of any two of the sticks pass the free version of MEMTEST86? Or do some fail?

 

[Obviouslyray]

Everything worked on memtest86. Matter of fact I tossed in an old 13 8100 and all ram slots worked perfectly with all 4 installed. It is a cpu issue. Disappointed but happy that the issue was solved. Thank you for the response!