New memory FAILED Moving Inversion and Advanced Pattern test

I have a new Corsair vengeance 5185 desktop PC.

It came with 16GB of memory (8GB DDR4 2667 MHz CMWB8G1L2666A16W4)

I added 2 more 8GB sticks (8GB DDR4 2667 MHz CMW16GX4M2A22666C16)

All 4 sticks are Corsair Vengeance RGB PRO 8GB @ 2666MHz.

The corsair diagnostics software fails Moving inversion and/or Advanced Pattern tests when all 4 sticks are installed. I can install any two sticks in any two linked slots (banks 0 & 2 or banks 1 & 3) by themselves and it passes all memory test. It only fails the test when all 4 sticks are installed. I switched them around in an attempt to verify if there's a bad stick or a bad bank on the mobo but they all work fine until all 4 sticks are installed.

The only way I know there's an issue is by using Corsairs diagnostic software, the system is reading 32GB, it acts completely normal. I have not done anything that will tax the memory yet but I would like to know if this is a common issue or if there is a underlying problem that can be resolved.

Is there a chance the two new sticks are not compatible with the sticks that came with the PC? They are the same brand, series, size and MHz. The only difference I can see on the label is the version is different and the new sticks are labeled 16GB (2x8) and the sticks that came installed just say 8GB on each.

I'm hoping someone will know that the memory is not somehow compatible with each other so I can just order new memory but I don't want to waste the money until I know. Or is there possibly a BIOS setting I can change to fix this error?

I will attach a few screen shots if it helps.

Unfortunately this is a common result when mixing two different types of memory. Just because they are of the same brand, same heatsink, same timings does mean they will work together. The physical material the RAM is made from is important and when you take two that come from different batches, your odds of success go down. Sometimes you can play with timings, tweak IO/SA voltages, and get things stable, but it is weeks of work and there is no guarantee of success. I don't recommend this for people unless you really understand what you are getting into and have some experience with memory training. I do, but I still won't do this. It is a splitting headache most of the time and often ends with the need to do a fresh install of the OS by the time you are done.

Your added 16GB kit has an extra "2" and should be this: CMW16GX4M2A2666C16

The first kit I cannot source, but that may be because the complete PCs from Corsair come with special parts not available to the public. I don't know how much this impacts your chances of success, but the Vengeance and One computers usually have special rules.

In the end, if you really think you need to move up to 32GB and want plug an play success, you need to buy a 32GB kit and replace all of your modules. I recently did this thinking I should as my usage was getting to be around 10/16GB or effectively 10/13.9 available. However, now on 32GB Windows just uses more for the same tasks. It's not faster or better. Now I had other aesthetic reasons for updating the RAM at that point, but unless you are doing something very specific that requires 32GB, you can still wait.

I think I understand. I have not built a PC in 8/10 years. I remeber you could buy matched RAM but it was not very picky about size or brand as long as you stayed in the same MHz range.

So the bottom line is if I want 32, or 64 I need to buy them as a "kit" in one package to avoid issues correct?

If so I might as well get something that runs faster...

Yes, buying in a "kit" guarantees compatibility. Not buying in a kit ... may or may not work. DDR4, in general, is much pickier than previous generations of RAM.

And ... tbh ... the RAM may work fine in real-world conditions but not pass tests. Hard to say but I do understand your reluctance.