[hleV]

I'm having an issue with the first 2 RAM slots (DIMMA1, DIMMA2) not recognizing RAM and thus not POSTing when the RAM stick is in either or both of them. The last 2 (DIMMB1 and DIMMB2) work fine.

Mobo: MSI Z370 Krait Gaming
CPU: Intel i7-8700K
RAM: G.Skill RipjawsV 16GB (2x8GB) 3000MHz C15
BIOS: 7B46v11 (newest)
PSU: EVGA SuperNova 650 G2
Cooler: Hyper 212 EVO

This issue was since the beginning (first 2 RAM slots never worked for me). I RMA'd the mobo, they said it works fine for them. I RMA'd the CPU - they said it works fine for them. I don't see how it can be the RAM, though I don't have other DDR4 to test. All components are brand new (the cooler is mostly new). I don't suppose my local shop RMA tested it with the same components, perhaps there's some really weird incompatibility or something.

There's an "EZ Debug LED" panel on the mobo. When RAM is inserted into 1st/2nd slots, it blinks RAM (long) and CPU (short).

So I'm out of ideas. Anyone ever had such an issue? Anything I could try?

 

[Mars73]

Got the exact same thing!
When I first put in my RAM sticks it was on slot A1 and B1 (and later A2 and B2) to be dual channel. But it wouldn't boot, everything was on but no picture.
So I thought I had fried my motherboard or something. But then I tried both sticks on B1 and B2 and behold I got picture and it would boot.
Removed my CPU to see if there were any bend pins, I think I saw some but not sure, tried putting everything in place but it still only works with B1 and B2.
Don't see any issues with my daily things and running games, but I'm also curious why this is.
btw I'm using Corsair Valueselect 2133MHz memory. I want to buy some 3000/3200MHz memory but not so sure because of this weird issue.

 

[arik]

I have the same issue with my Z370 Tomahawk. Same processor, same memory.
Same Debug-LED information.

 

[hleV]

Received a call today from the RMA shop, they found some incompatibility with the components (I gave them everything: mobo, CPU, RAM, to test them together as separately they couldn't find the issue before) and they offered to choose another motherboard.