Information - AsRock Rack X470D4U Motherboard - Gohan's Mishaps! :)


Hey everyone!

Gohan’s back with his lastest :slight_smile:

So, a bit of premise here.

I decided to finally build another Ryzen server. Since I have been super duper happy with my Reeezen Build and I was ready to have another one!


CPU: Ryzen 5 2600 (Non-X)
RAM: Reused 2x 8GB DDR4-2400 NON-ECC Corsair LPX Vengeance
MOBO: ASRock Rack X470D4U

Now, since this is mostly for information. I am going to cut right to the chase.

The X470D4U from ASRock Rack is a very weird motherboard…

First of all…

CPU: This motherboard can support ALL Ryzen 2nd and 3rd Gen CPUs. Including the PRO series chips, which are not available for boxed retail purchase.

The ECC memory support is heavily dependent on the actual CPU series.

Per ASRock "For Picasso Ridge and Raven Ridge CPUs, ECC is only supported with PRO CPUs."

Now, this means that theoretically every other CPU in the 2nd and 3rd Gen lineup supports ECC AND Non-ECC memory

CPU (ECC Memory) Support List

GREEN - ECC and Non-ECC Supported :white_check_mark:

Speaking of memory. :thinking:

The Ryzen 5 2600 supports a MAX of 64GB per AMD
(Now these kinds of claims have been disproven before with many intel CPUs and what not, so who is to really say what the upper memory limitation actually is?) :thinking:

However, the ASRock X470D4U has been proven to support 128GB of DDR4 ECC memory per ASRock both in the manual and the Memory Support QVL List.
They specifically list a 32GB DIMM from Samsung
( DDR4-2666 ECC 32GB Samsung M391A4G43MB1-CTDQ )

X470D4U Memory Compatibility

I had a major issue with installing Windows (10, server 2016, server 2019) It did not matter which version, which PCIe cards were installed, whether it was M.2 SATA3 or M.2 NVMe, etc. Upon completing the installation from USB, it would BSOD with STOPCODE “DPC Watchdog Violation”

After countless hours of troubleshooting and googling around. Many people mentioned having this error when dealing with older B350/X370 chipsets and the 1st Gen Ryzen CPUs (which were picky asf about memory)

My Reeezen Build was running a B450 Aorus Elite and XPG Gammix D10 RAM with no issue whatsoever, so it was a major problem to finally discover that I had a RAM compatibility issue with the ASRock X470 motherboard.

Apparently the Corsair Vengeance LPX [DDR4-2400] (CMK16GX4M2A2400C16) is NOT compatible with this motherboard… I had countless DPC Watchdog Violation BSODs.

I decided to put the XPG Gammix D10 in the new X470 server instead. (I performed a switcharoo)

Memory Testing Results

The XPG Gammix D10 works FLAWLESSLY in the new X470D4U motherboard, Windows installed with no issues, no warnings, no stopcodes, no BSODs, etc, etc (You catch my drift here) :smile:

On a side note, the B450 Elite Aorus with a Ryzen 5 2600 (identical CPU) accepted the Corsair Vengeance LPX DDR4-2400 memory kit with NO ISSUES as well…

So, this was definitely an odd issue, and thus worthy of a proper Sudo.Fail post!

Now that that is resolved, lets move on shall we?? :wink:

Board Layout!

Now, the board layout diagram here is pretty odd. All things considered!

We know for fact that the Ryzen Series CPUs have a total of 32 PCIe Lanes on the die itself. AM4 can only use 24 PCIe Lanes max.

I personally feel that they could have worked this board a bit better in regards to the PCIe Lane Allocations.

The biggest limitation is the M.2 NVMe slots.

Both slots support NVMe, but only 1x supports SATA3 M.2 SSDs.

Now, the support isnt bad at all. I commend ASRock for thinking about this objectively, but the execution is kind of poor for such an expensive motherboard.

The Primary M.2 slot has either PCIe 3.0 x2 support or SATA3 SSD(which most if not all NVMe drives have a minimum of x4 for maximum performance)

On top of that, they allocated PCIe 2.0 x4 for the 2nd NVMe slot.
This truly defeats the entire purpose of most if not all Modern NVMe drives.


Now, one of the COOLEST features is the PCIe Bifurcation capability of the primary PCIe Slot.

You can “split” the x16 slot into x8/x8 or x4/x4/x4/x4

This can allow you to take advantage of many different types of PCIe Hardware that can make use of this board specific feature.

One of such add-in cards is ASRocks own Ultra Quad M.2 Card
or the ASUS Hyper M.2 X16 Card

These x16 full size PCIe cards let you run 4x NVMe modules at maximum performance. (Until you eventually hit a PCIe Bus throughput limitation of course! LOL)

Another feature is that PCIe Bifurcation can allow you to use MULTIPLE PCIe cards with 1x Full Size x16 slot!!!

How you ask???

Depending on the motherboard, and the BIOS level Bifurcation support,
(x16 mode , x8/x8 mode , x8/x4/x4 mode , x4/x4/x8 mode, x4/x4/x4/x4 mode)

You can potentially take advantage of a Bifurcated or Trifurcated Riser card.
Ameri-Rack makes such a card.
Now, doing such a thing just means that you are dedicating a portion of the PCIe lanes to that specific card, so this could get complicated pretty fast. YMMV of course

Full Motherboard Diagram - PCIe Slot Order

Now, this is an interesting design.

PCIe 6 Top slot is full x16 both physically and electrically (sharing lanes with PCIe slot 4)
PCIe 5 Middle slot is physically x8 open ended, but electrically x4 only
PCIe 4 Bottom slot is physically x16, but electrically x8 (sharing 8 lanes with PCIe 6)

Since PCIe 4 shares x8 lanes with PCIe 6, this means that if both are in “use” then they will both only run in x8 mode


10x SATA connectors on-board.
1x USB 3 header
USB 3.1 Gen1 I/O Ports.
Dual Gigabit Intel LAN

ASRockRack seems to have been very generous with connectors/ports availability.

CPU Coolers??? :thinking:

The X470D4U has a different CPU Socket + RAM DIMM Slot layout then most boards.

As shown above, (top X470D4U, bottom X470 GAMING PLUS MAX)

The X470D4U socket and dimm slots have been turned. This is due to being a “server” class motherboard. This design change was done in anticipation of directional airflow in a rack mounted server chassis. By turning the socket and dimm slots, they have made it so the RAM will not block the socket from an airflow perspective.

Normally this type of foresight would be praised, however… There are some serious concerns.
One being that no manufacturer makes a 1U/2U Passive CPU cooling block for AM4. (this is a problem for those of us wanting to run high end CPUs such as the 2700/3700x or greater which generate a large amount of heat under load.

Issue #2 is that by turning the socket and dimm slots. They have limited CPU cooler compatibility by about 90%. You will NOT be able to use a Wraith Stealth Stock Cooler, Wraith Prism Stock Cooler, or a Noctua L9x65 AM4… and many many more. This is due to the clearance between the socket and the dimm slots.
As shown here in an imgur album.


My original conclusion was that it was not worth purchasing due to BIOS quirks. Since then, ASRockRack has provided me with a Beta BIOS (L3.34) below. It has resolved a number of issues that I originally encountered, and fixed the PCIe Bifurcation capability.

Currently, I am running 2x of these motherboards. 3950X w/ 4x 32GB Vengeance LPX DIMMS.
and a 3700X w/ 32GB Total RAM (DDR4-3200). Both work great, and I have noticed much improvement with the Beta BIOS.

Give it a try, and leave some comments below if it helped you in anyway. :smiley:

Article Update:

AsRockRack AM4 X470D4U Server Motherboard
Beta BIOS L3.34 (

  • Fixed/Added full PCIe Bifurcation Capability on Slot 6
  • Resolved an Issue with Corsair Vengeance LPX (2x32GB) Kit (Dual Sticks not posting, but single will) (Fix: Both sticks work no problem now)
  • Noticed faster boot speeds
  • Faster HW Sensor response
  • Faster movement inside the BIOS menu
  • Perhaps more has been done, but that is all I have noticed currently.

NOTE: No GPU required since the motherboard has the built in ASPEED 2500 BMC module which features on-board graphics (basic of course)