Need help figuring out RAM issues and crashing

[Rubbler]

Hi everyone, I just this past week ordered a pile of parts and am building my first new PC in almost 10 years. 
I got a Ryzen 9 7900X3D, Asus Prime B650-plus, 2x16GB T-Force Ram kit amongst other parts. 
My issue is the build went fine, seemed like everything is working. Loaded into Bios and all hardware shows up correctly even before upgrading to newest bios. 
The RAM shows both sticks correctly, life is good. 
Windows however crashes almost instantly whenever I have both DIMMS installed. I’ve tried each stick by itself in slot 2/4 and both work perfectly in those slots. Windows is rock solid, no problems. 
As soon as I put both sticks in again and again, crashes. If I put them both in slots 1/3 the system won’t even boot. 
All this leads me to believe the RAM is fine since both sticks behave fine by themselves. 
Is the MB messed up in this situation? I would have figured it would not load the RAM in bios correctly but it looks fine. Windows is the only issue. 
I have no other DDR5 to test with as like I said, first build in forever. I will buy more of I have to but I’ve already spent $2400 CAD and really already went over budget. 
Is there anything else to try or should I return the MB?

 Any help would be super appreciated. 
Also, when Windows dies there’s absolutely nothing in event viewer that shows an issue. Not sure where to go from here. 

[AS185]

Hey,

According to the manual, if you installed the 2 RAM modules into DIMM_A2 and DIMM_B2 everything should be working fine, as you mentioned. Technically, the system shouldn't even boot if you put into DIMM_A1 and DIMM_B1. There's no need to return the motherboard. Keep the random access memory kit in the initial slots and enjoy your brand-new computer.

[Rubbler]

The issue is as mentioned however when I have both sticks loaded in those slots it crashes constantly inside windows about 30s after loading the OS. Each slot works individually with either stick of ram but I can never use the full 32GB without a crash. 

[achugh]

Hi @Rubbler , I am sorry to hear about your troubles.

You mentioned that you did not update BIOS. BIOS updates typically improve memory stability. I recommend that you give it a try. You can always flashback to your current version, if needed.

You also did not mention if your memory kit is on the QVL for your board?

Windows crashes are typically related to memory instability and it seems your two sticks are together not playing nice. Did you enable any of the EXPO settings in BIOS? If yes, you can try setting it back to AUTO and start from there to solve your issues. Basically you should press F5 to load defaults and not touch anything just to see if your crashes go away or not.

I hope this information helps you make progress towards solving your issue.