Question RAM doesn't work in channel B, but does if all slots are filled?

[TheBlueMan15]

So I just built my new PC, and here's my issue:
1. Mobo is a dual channel, 4 slot RAM config (A1/A2/B1/B2). When I put RAM into slots A2/B2 (as the mobo manual said to for dual channel) I get a 'memory PMU training error at socket 0 channel 0 DIMM 1', and the BIOS only detects one stick (8GB).
-This is the same for slots A1/B1.

2. I tested the RAM sticks individually in each slot and booted, it boots fine for both sticks positioned in A1 or A2, but not in B1 or B2.
- I put sticks in A1/A2 and it detects 16GB as it should.

3. I borrowed 2 sticks from my friend and put them in (so all 4 slots are populated) and it detects 32GB as it should.
- I then tested his RAM in the same way I did mine, same problem as before with B1/B2.

4. I updated to the latest BIOS and there's no difference. Everything else works fine.

What is going on and how do I resolve it?

Specs:
Mobo: Gigabyte X570 Gaming X
CPU: Ryzen 5 3600
RAM: Corsair Vengeance LPX 2x8GB 3600MHz
GPU: RTX 2060 6GB
CPU Cooler: Cooler Master ML240L AIO
Storage: 500GB NVMe, 2TB HDD
PSU: GameMax RGB 550W

Secondary RAM: Patriot Viper 2x8GB 3200MHz

 

[Deleted member 14196]

I think you have a problem with your motherboard

 

[TheBlueMan15]

I think you have a problem with your motherboard

If it was a motherboard problem like a dead DIMM slot, surely it wouldn't pick up the RAM in that dead slot at all? Rather than only with all 4 slots filled

 

[Deleted member 14196]

Maybe the two ram sticks you bought for it are not compatible

 

[TheBlueMan15]

Maybe the two ram sticks you bought for it are not compatible

But they work in slots A1/A2? Both sets of memory work in slots A1/A2, but not B1/B2.

The Corsair RAM I initially put in is compatible, it's on the Gigabyte supported list for AMD Matisse processors (which is what the 3600 comes under)

 

[Deleted member 14196]

Look if they’re not working in the proper slots then you have a motherboard problem. Use memtest and test each stick in eac slot. One at a time. You need to figure out if you have a memory stick problem or a motherboard issue

 

[ex_bubblehead]

First question: Are these memory sticks part of a factory matched set? (Meaning that they were packaged together in the same package at the factory)

Second question: Does this specific memory model appear on the tested/approved list for this CPU/motherboard?

Third question: Have you checked both the CPU, for bent/missing pins and the CPU socket for obstructions/damage?

There are only a few things that could be wrong here:

Wrong RAM (Not on the tested/approved list)
Bad RAM
Bad RAM socket/s
Bad CPU socket
Bad CPU (the memory controller resides in the CPU)

Any one of these requires an RMA of the offending part/s. In the case of RAM both sticks must be returned, even if only one is bad as they are matched.

 

[AngelJin]

Also consider this when coolers are installed too tight or tightened unevenly , it can cause the memory slots to not function.