ECC memory for ASRock RACK X470D4U

[MGone]

My 'on paper' specs have taken a bit of a tangent and I've been looking at Ryzen builds as a possibility on the X470D4U motherboard.

But I'm having a really hard time trying to find any of the rather limited ECC QVL memory.

I manged to decode the module name for the Samsung 32GB ECC 2666 DIMM (M391A4G43MB1-CTDQ) using this guide (except the 'Q' and I'm unsure how to interpret that). The rest gives me the following:

M: Memory Module
3: DIMM
91: x72 288pin ECC Unbuffered DIMM
A: DDR4 SDRAM (1.2V VDD)
4G: 4 Gang depth
4: 16Banks & POD-1.2V
3: x 8 Bit Organisation
M: 1st Generation
B: FBGA (Halogen-free & Lead-free, Flip Chip)
1: PCB Revision 1st Rev
C: Commercial Temp.(0°C ~ 85°C) & Normal Power
TD: DDR4-2666 (1333MHz @ CL=19, tRCD=19, tRP=19)
Q : no indication of what this might be, other than the label suggests Memory Buffer....maybe Q means no buffer?

I've had one source say they might be able to get sticks that have the same code but without the Q, but they were not 100% confident in that.

So my question is which bits are important to ensure compatibility?

If I find any 32GB DDR4-2666 288pin ECC 1.2v Unbuffered CL19 DIMM modules should they just work, or am I rolling the dice?

 

[Christian K]

In my opinion the mainboard QVL memory list is nothing more but a vendor-verified suggestion.
The mainboard 'just' guarantees wiring that satisfies the physical requirements for DDR4, in this case.

More important is the memory controller residing in the CPU. As of today with a recent BIOS my Ryzen 1600 Truenas Build is eating happily all kinds of DDR4.

To answer your questions,
the memory should be DDR4 compliant, unbuffered DIMM.
ECC is ok, AsRock does not cripple ECC functionality entirely. be sure to unset "platform first error handling" in the EFI and ECC detections should be reported to the kernel.
Memory with the MIcron E Die seems to work superior with Ryzens memory controller, according to massive amounts of success stories and my personal experience. I run Kingston ECC memory with MIcron chips.

 

[jgreco]

the mainboard QVL memory list is nothing more but a vendor-verified suggestion.

It isn't even quite that. It's a statement by the vendor that they tried a particular type of DIMM at full capacity and had no issues. However, manufacturing runs vary, and there's the infamous example of the Elpida UDIMM's on Ivy Bridge E3 CPU's where a bunch of Kingston (etc) DIMM modules ended up not working in full-population scenarios despite previous vendor testing, thought to be due to a minor PCB design change in the DIMM.

Use QVL memory if you really need to improve the odds that your memory will work. If you live next door to a Micro Center and can just walk across the street to return memory that doesn't work, BUY WHATEVER WORKS. If you live in Antarctica, deliveries take six to nine months, and you can't afford the back-and-forth delays, buy the QVL stuff.

For Supermicro, here at the shop we look very carefully at the memory specs for Supermicro-labeled parts, which have an OEM part number on them. It's almost always safe to use the OEM parts, since the main difference is that they didn't stop in San Jose for a Supermicro sticker application. But it's also quite normal for a QVL part to be discontinued by the OEM, and then you need to carefully look for the closest "newer" part match, and that almost always works fine too.

 

[Constantin]

I second that though my board was picky enough where a single revision difference in the RAM die generation apparently was the difference between a working and a non-working system. Like @jgreco, all was well if I only tried to fill 50% of the RAM slots, but a full 128GB load-out would not post unless every single character on the RAM SKU matched the one on "Tested Memory List" letter for letter.

 

[MGone]

Thanks folks...I was hoping to get QVL, but this list is super short!

Type	Speed	DIMM↑	Size	Vendor	Module	Part No	Cell
DDR4	2666	ECC	32GB	Samsung	M391A4G43MB1-CTDQ	901 K4AAG085WM BCTD	Sec
DDR4	2666	ECC	16GB	Kingston	KSM26ED8/16ME	8CE75D9VPP	Micron
DDR4	2666	ECC	16GB	Samsung	M391A2K43BB1-CTDQ	K4A8G085WB BCTD	Sec
DDR4	2400	ECC	8GB	Hynix	HMA81GU7AFR8N-UHT0	H5AN8G8NAFR	Hynix
DDR4	2400	ECC	16GB	Hynix	HMA82GU7AFR8N-UHT0	H5AN8G8NAFR	Hynix
DDR4	2133	ECC	16GB	Crucial	CT16G4WFD8213.18FB1	6YB75D9TBH	Micron

That's it for ECC!

I also noticed this in the motherboard manual...

Does this suggest that with say, a Picasso chip and 2400 or 2666 memory you would be reduced to one or two slots dependant upon ranking? Doesn't this negate the benefits of double ranked memory? Or is it simply saying you can't have your cake and eat it!

Looking at the QVL again:

• there's no 3200MHz ECC so that's not going to be an issue.
• The 32GB 2666MHz Samsung module is 2Rx8. Does the table mean that you could only run a single stick with the Picasso, Raven Ridge and Pinnacle chips, but could run two but not four sticks with Matisse? (so 64GB max) Is this a function of the CPU? Here for Vermeer chips (not on this motherboard though) it says:

Channel A	Channel A	Channel B	Channel B
DIMM0	DIMM1	DIMM0	DIMM1	Max. Data Rate (MT/s)
-	SR	-	-	3200
-	DR	-	-	3200
-	SR	-	SR	3200
-	DR	-	DR	3200
SR	SR	SR	SR	2933
SR/DR	DR	SR/DR	DR	2667
SR/DR	SR/DR	SR/DR	SR/DR	2667

Apologies if this all seems like stupid questions!

 

[Jokener]

The table shows the rated speeds for the different possible combinations of DR or SR modules in the RAM slots.
For two DR sticks in slots A1/B1, the Picasso/RR and Pinnacle Ridge processors are qualified as supporting DDR4 2400 speeds, while Matisse is qualified at DDR4 3200.
If you add two more sticks and use all four slots with DR modules, those speeds drop to DDR4 1866 (or 2400 for Matisse).

I use 64GB total in four sticks of Kingston KSM24ED8/16ME on this board without any issues.

 

[MGone]

The table shows the rated speeds for the different possible combinations of DR or SR modules in the RAM slots.
For two DR sticks in slots A1/B1, the Picasso/RR and Pinnacle Ridge processors are qualified as supporting DDR4 2400 speeds, while Matisse is qualified at DDR4 3200.
If you add two more sticks and use all four slots with DR modules, those speeds drop to DDR4 1866 (or 2400 for Matisse).

I use 64GB total in four sticks of Kingston KSM24ED8/16ME on this board without any issues.

I ended up going for 2x32GB sticks of Integral that said EQV. TO M391A4G43MB1-CTD SAMSUNG...It's missing the Q at the end but fingers crossed that's not a significant spec detail as I couldn't find any information on it!

I'm just waiting for a few bits and the weekend to start putting it together! All my time is spent on organising a Cubscout camp at the moment so this project has taken a back seat!