64GB memory installed but only 32GB detected in UEFI BIOS and OS

Question

I have extended my memory to 64GB (4x16GB) and noticed a strange behavior: First the mainboard doesn't boot and turned of automatically. Then I updated the UEFI (changelog shows memory compatibility improvements) and now it boots. But the UEFI reports only 32GB of total memory size, even it recognizes 4 RAM sticks with 16GB each:

So the OSes itself seems to get only 32GB avaliable too. Linux shows me 32GB and Windows has a interesting thing: It shows in the system properties that 64GB were installed, but only 31,9GB useable:

The RAM sticks are not equal (different manufacturers and clocks) but I don't get it why 64GB were detected with only 32GB usable. I only remember this from 32 bit OS installations, which could only manage 4GB even when e.g. 8GB are installed.

What is the problem and how can I fix it?

Things I already tried:

• Double checked the specs, my board can handle up to 128GB
• Checked msconfig for memory limits - found a lot of posts about this, but I don't had a limit set (I even think the problem is not in the OS when already the UEFI detect only 32GB of total memory)
• Plugged one memory stick out - it still says 32GB total memory, but detect the bank as empty in the screen above
• Replaced one 16GB stick by a 8GB stick - the same result as above

Update: Also happens on two identical Crucial module

To investigate the issue, I just inserted the two Crucial sticks in dual channel mode, because they were idential (model and speed). The mainboard documentation recommends this setup (and says A2 has to be used first), so I installed it like on the graphic in the middle:

Even this doesn't work, the UEFI only detects 16GB (instead of 16GB * 2 = 32GB):

But when I move the B2 module to A1, it shows the following warning:

Now the board detects 32GB as memory size, as well as my Linux/Windows OS. So it seems non-dualchannel mode works, where dualchannel don't work with identical modules any more. Cause the suggestion moving A1 to B2 was the recommendation from the docs, which I tried first (and only detects 16GB).

Seems very curious to me cause I used two identical modules which were even sold as kit: 32GB Crucial Ballistix Sport LT V2 Dual Rank grau DDR4-3200 DIMM CL16 Dual Kit

Update 2:

Since the MSI Dragon Center didn't update my bios to the latest version, I tried to update it again. Now I'm on HB0 from 10/30/2020 instead of HA0 from 09/07/2020. And I also upgraded from the Ryzen 5 2600 to the Ryzen 7 3700 cause the 2600 was only a temp solution and I found some people having RAM issues with older Ryzen CPUs:

It seems promising that 7C37vH9 has Improved memory compatibility in the changelog, but still the same problem. I'm wondering about the version and date, since both are not present in the changelog on the MSI homepage. The homepage lists 7C37vHB from 2020-11-04 which isn't shown in MSI Dragon Center. After upgrading to 10/30/2020 I searched again with Dragon Center, it says that my bios is up2date.

Update 3: Two new modules with the same clock won't work too

I bought 2x16GB modules with 3200 MHz so that I have 4 modules with the same speed. When I insert more than 2 modules or don't use the first 2 slots near the CPU, the system won't boot. The fans are running at 100%, no picture appears on the screens and the DRAM debug LED is on.

I took the pic later, here the BOOT Led is on, it's just for demonstrating purpose:

This seems not an issue of the RAM. All 4 sticks work, when I place only two of them against the dual channel recommendation. Then I get 32GB as expected, until I

• add a 3rd or 4th module additionally to the 2 ones installed against dualchannel. It doesn't matter which slot I use for them.
• place two modules in the dualchannel mode, as recommended in the docs

In both cases, the system won't boot and I get no screen.

Update 4: Strange memory frequency

I took a look in the overclocking settings. I haven't overclocked anything, just would like to look if I find something that could explain this strange behavior. The frequency is set to auto, so it should be 3200 MHz when two sticks with those clock are inserted.

But it reports 2666MHz:

MSI Dragon Center show me a similar (but not exactly the same, 1MHz difference?) frequency of the memory modules, when I export a system info:

Memory:                       32 GB @ 
                               - 16 GB DDR4-2667, Unknown BL16G32C16U4B.M16FE
                               - 16 GB DDR4-2667, Unknown BL16G32C16U4B.M16FE

I also tried to change the DRAM Frequency setting from Auto to 3200, in the Bios, still no difference.

Answer 1

I've seen motherboards that would have a big problem with this setup: Note that you have some 2933Mhz chips and some 3200Mhz chips. While I have seen such mismatches work I have also seen them exclude the slower chips and I have seen them not boot at all. I have also seen the order of the chips make the difference between work and not boot.

All chips should have the same specs and ideally should be identical.

Answer 2

Simple things first:

Whenever you are having problems with memory, it is worth updating your BIOS to the latest version. I don't know if this is the cause, in your case, but there have been several recent updates to the BIOS Since your version including 7C37vH9, with changes including improved memory compatibility.

The updates are available on the MSI website.

Testing the memory:

Consider running memtest86 on the memory modules to check for errors.

Still having problems:

It is, as I understand, fairly common to have incompatibilities between two sets of modules of different brands and/or different speeds. It can even happen with modules from the same supplier but different batches. Kingston support replaced some modules of mine under lifetime guarantee and they insisted on replacing all 4 even though one was faulty, as they come across similar incompatibilities from time to time.