Question RAM compatibility with motherboard & CPU

[black_swordfish]

Given:
I have deployed running system as a NAS which runs fine. After the setup I have discovered that original 16GB of RAM are not enough, therefore I have bought used RAM for replacement. After trying to start the system with the replacement RAM system does not POST and repeats cycle of 5 short + 1 long beeps.

Specs:
MB: Supermicro X11SAE
CPU: Intel Xeon E3-1245 V6
Original RAM: 2x Micron MTA16ATF1G64AZ-2G1B1 8GB PC4-2133P
Replacement RAM: 2x SK Hynix HMA42GR7AFR4N-UH 16GB PC4-2400T

So far I have tried the following without any effect (old RAM was removed prior installing the replacement):

• Putting in a single stick of replacement RAM (each stick separately).
• Double checked correct RAM slot population sequence on MB (filling blue ones from CPU side).
• Checked that both CPU and MB has 2400 MT/s supported.
• Resetting BIOS to default settings.
• Setting Max RAM speed in BIOS to "2400" (here I was already quite desperate tbh).
• Updated BIOS to the latest version afterwards resetting CMOS etc.

Conclusions I came up with:

• Beep code cycle means "no memory (RAM) installed", so either MB or CPU is not compatiable with intalled RAM.
• Both original and replacement RAM are DDR4 ECC type and physically the same, so there is no issue here.
• Probability that both replacement RAM sticks are deffective is quite low.
• The only problem area is speed - either MB or CPU does not actually support 2400 MT/s.

Questions:

• Do these conclusions look right or there is something I have not noticed?
• Any ideas what else I should try/do?
• If I need to look for 2133 MT/s RAM what are the odds that RAM kits not actually validated by Supermicro for this MB would not work (considering that I stick with Samsung/SK Hynix/Micro)?
• Do I read it right that CPU supports only 2 memory channels meaning that out of 4 slots on MB I can actually use only two of them?

 

[Aeacus]

there is something I have not noticed?

SK Hynix is RDIMM (Registered) RAM, while Micron RAM is not (Micron is UDIMM).

Also MoBo specs doesn't say that MoBo supports RDIMM (Registered) RAM. Instead, MoBo supports either ECC or non-ECC UDIMM (unbuffered) RAM.
MoBo specs: https://www.supermicro.com/en/products/motherboard/x11sae

So, i think your issue with RAM lies in there.

 

[SkyNetRising]

Conclusions I came up with:

• Both original and replacement RAM are DDR4 ECC type and physically the same, so there is no issue here.

Original ram is non-ECC, unregistered (basic desktop ram)
Replacement ram is ECC, registered (server ram).
Your motherboard doesn't support registered ram.

 

[black_swordfish]

Thanks to both of you for the answers, indeed - original RAM turns out to be non-ECC, while the new one is ECC, which both are supported. However as noted RDIMM (which is my replacement kit) is indeed not supported by MB.

I have filled the gap by reading MB manual to understand that 2 memory channels are linked to 4 physycal DIMM slots , so no limitation there.

My last question is does the motherboard support 2400 MT/s memory? I see it listed on the Supermicro product page, but manual in multiple places lists only 2133. Any ideas how to find out without buying & trying?

 

[SkyNetRising]

My last question is does the motherboard support 2400 MT/s memory?
I see it listed on the Supermicro product page, but manual in multiple places lists only 2133.
Any ideas how to find out without buying & trying?

2400mhz ram can work in 2133mhz mode. That's not a problem.
But yes - your motherboard and cpu supports 2400mhz ram.

Just don't buy registered ram modules and you'll be fine.

 

[Aeacus]

My last question is does the motherboard support 2400 MT/s memory?

It should work just fine. And even in a slight chance 2400 MT/s won't work, you can always run the RAM at 2133 MT/s since that is JEDEC default and all DDR4 RAM sticks and kits can run at that speeds.