by the way, can any one confirm Asrock can have 4+4+8 or 8+4+4 bifurcation?
Asus only supports 4+4+4+4 or 8+8. The bios file dump also indicates that they did not hide anything.
what’s the last Q-code shown before it reboots itself?
what’s going on if you remove the NIC and HBA but leave 4 GPUs? If it boots, it means that your PSU is not powerful enough or Asrock should add another 12V input plug as ASUS did or you psu is not powerful enough?
Why not all lanes are used? I mean is there any practical reason why it’s partitioned this way? It feels weird to have 12 spare lanes and two x8 slots instead of x16. I mean I know it’s not all that big loss but hey… I paid for 128 lanes I wanna use 128 lanes xD
It’s hard to read the last Q-code because it continuously cycles through the same sequence again and again. Here’s a youtube video. I think it is 42. The complete sequence is 00 > 3E > 68 > 91 > d2 > 14 > 15 > 14 > 15 > 6E > 15 > 6E > C2 > C8 > C9 > C4 > 07 > 42 > 36 > 9A > 62 > 42 > 00. At time code 00:39 you can see that it’s starting again at 00.
If I remove the NIC & HBA the mobo boots just fine but I doubt that my be quiet! Straight Power 11 850W isn’t powerful enough because I’m measuring the power draw at the wall with a tasmota flashed smart plug and no point in the boot process there is a draw above 850W not even spikes. I find it more likely that ASRock missed out at adding another 12V input plug but then what is the point of having 7 PCIe slots if I can’t actually use them because of power issues?
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I tested some more PCIe devices and I’m pretty sure that the issue is caused by ASRock not including a second 12V input plug because I’m able to populate all remaining PCIe slots with Mellanox X3 PCIe 3.0 x8 devices and the mainboard boots just fine. As soon as I connect a PCIe 2.0 x8 device like a LSI SAS2008 HBA or a Intel X520-DA2 the mainboard doesn’t boot anymore. Also tried adjusting the PCIe speed to 2.0 in the BIOS but it didn’t make a difference. Curiously PCIe 2.0 devices like a Blackmagic Intensity Pro 4K with 4x lanes are working as well.
@wendell Can you confirm this? Or is there someone else which owns the board and can confirm or deny my findings.
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So you are able to boot with
- CX3 + 4GPU
- CX3 + 3GPU + 2008
In this case, you have a power issue. You may want to measure the 12V voltage with a multimeter on those plugs. However, I doubt it can be detected. Usually it is more obvious on the pcie 12v pins since Asrock might not design the 12v power delivery plane properly.
I had a 5V device that fails due to similar issue, when I measured the voltage directly on the pcb of that device, when it boots it dropped to very low. So I optimized the power and it works now.
it;s just a pcb routing issue. if they want to route all using the current number of layers maybe more testing required. Or they can add layer, which adds cost. Well, they are positioned not that high end (compared to the asus one).
the asus one has 7 x16 pcies. only $100 more.
Yes but can the Asus do pbo? Nope 
Yeah well that’s related to my previous comment. I believe ASRock mobo had potential to be top-end mobo. Asus mobo is really meh and underwhelming honestly to me. For 100$ more you get no TB4, no dedicated IPMI, no VGA in the back, less OC features and more compatibility issues related to fact that it’s giant SSI-EEB board with connectors facing downwards because… reasons I guess. I use ASRock WRX80 Creator in mid-tower Fractal R6 so wouldn’t work for me.
But okay fair point. I guess I just have to live with that.
I don’t own a multimeter. How do I measure the voltage directly on the pcb? What do you mean by you optimized the power?
I just took a look at BIOS and there’s no such option available in BIOS. That said long time ago I asked ASRock for x8/x8 bifurcation on old x399 board and they just sent me modified BIOS build after few weeks so I believe soneone could just ask support for that. They seem to be really cool guys.
there is not much you can do to optimize here. since it is by design (from asrock)
multimeter is just to verify the claim it’s a power issue.
sounds cool. asus ignored my request for a 844 bios (it’s their turn to take the shame after asrock took the shame for bad power deliver design)
There’s no space on the IO shield for the VGA connector. But the motherboard includes a VGA connector bracket that you can put into one of the PCI slots and connect to VGA header on the motherboard.
The connectors are facing downwards so that you can insert a 2 / 3 slot GPU in PCIe slot 7 and let it hang of the motherboard and still be able to connect the cabes to the downward facing headers.
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My 5975wx CPU arrives in. Few hrs… Tracking says "out for delivery " can’t wait
I was able to borrow a Radeon Pro W5500 with a dedicated 6-pin power connector and swap it with the Radeon RX460. So now there are only two GPUs (2x GTX 1050 Ti) passively powered by the PCIe slots. Interestingly the Q-code has changed. It straight up goes to 94 and sits there forever.
According to this thread. 94 means:
94 - PCI Bus Enumeration 32
Just to confirm
So you are able to boot
CX3 + 4GPU
CX3 + 3GPU + 2008
Stuck at 94
CX3 + 3GPU + 2008 + W5500
If not, it would be better to make a table and list combinations tried and then logically analyze it.
Maybe something like this could help solve the power issue, as the daughter board has a separate 6 pin power connector. Though you would only have 8x PCIE 3.x bandwith.
But 94 - PCI Bus Enumeration 32 might be something completely else.
I haven’t used this riser setup. My attempt to use a different bifurcated riser (daughter board didn’t had separate power) wasn’t that successfull, I got one card barely running with a lot of PCIe errors and the other card was not detected at all. I solved it now differently.
Thanks for the recommendation but this is to expensive in order to workaround for a flaw caused by the manifacture in the first place.
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There is another issue with the board. The onboard VGA will not be respected as primary graphics if I also connect a HDMI dummy plug for any of the GPUs even though I selected the VGA as primary in the BIOS. This makes the feature essentially useless and I’m unable to use the KVM remote control.
I’m running proxmox and as far as I know there is no way to bind the framebuffer only to the ASPEED Graphics VGA in order to get a console for the KVM. I will have to add nofb nomodeset video=vesafb:off video=efifb:off to kernel options to get GPU passthrough working at all but then I have no framebuffer.
It gets even worse if I disable the onboard VGA and select PCIe as primary graphics I still can’t use the KVM because the framebuffer of the primary GPU will not be copied to the KVM.