ASUS ROG MAXIMUS Z790 HERO AND PCIe lines

[francoistoen]

HI
I need some help about PCIE lines and PCIE bifurcation.
First my configuration: (see picture)
Motherboard : Asus ROG MAXIMUS Z790 HERO
CPU Intel core i9-14900KF
GPU/Graphics : XFX RADEON RX5700 XT (PCIe 4x16) in extension slot PCIEX16(G5)_1
Memory : 2x16 Gbytes DDR5 Corsair
Storage
1 x SAMSUNG NVME M2 SSD 990PRO (PCIe 4x4) 1To in slot M2_1 (system)
2 x SAMSUNG NVME M2 SSD 970 EVO PLUS (PCIe 3x4) 500Go in slots M2_2 and M2_3
2 x SAMSUNG NVME M2 SSD 970 EVO PLUS (PCIe 3x4) 500GO 2 in Hyper card plugged in extension slot PCIEX16(G5)_2 in raid0 mode
1 x SAMSUNG NVME M2 SSD 970 EVO PLUS (PCIe 3x4) 2To in PCIE to NVME M2 adapter card in expansion slot PCIE16(G4)
2 x SAMSUNG SATA3 SSD 860 EVO 500Go
2 x SATA3 Hard drive 1 GO.

All this is perfectly detected, working but :
GPU-Z detect my graphic card as a PCIe4x8
Samsung magician detecte ALL the nvme SSD as PCIe Gen 2x1.

I need 16+4=20 PCIe4 lines (16 GPU and 4 for NVME M2 990 PRO)
I need 20 PCIe3 lines ( 5 x NVME M2 SAMSUNG 970 EVO PLUS)
and I don't know how to figure out the way to do it.
I know tha 6 NVME SSD M2 is too big for a motherboard designed for only 5.
I'm wondering if it is possible to have:
GPU 4x16
one NVME SSD 4x4
and 3 or 4 NVME 3x4
Hereafter I need 16 PCIe4 lines and 12 or 16 PCIe3 lines.
Some ideas about that configuration?
Thanks in advance

François

[JohnAb]

First off, if you want to use M.2_1 then you are only going to get x8 on the GPU. However, that will only result in a speed reduction of 5% max in practice, maybe only 3%, so not really an issue. 

My next thought is why you are only getting Gen 2 speeds on all of the SSDs. I'd suggest removing the Hyper card as a first step and just see what speeds you get then. I suspect that with that removed, you should get the expected speeds. Just try and see, it will helpful to understand your options better.  

Without the Hyper card, I would expect that all motherboard M.2 drives should be running at full speed. 

Another option might be to consider getting an external TB4 enclosure. I have one, but although the speed test results are good, about 3,000MB/s in tests, in actual use it's not really any faster than an external normal USB 10Gb/s external enclosure. 

I guess your decision will have to based on whether you need speed or capacity. 

[francoistoen · Accepted solution]

Hi

Thank you for your answer.

In fact I can use M2_1 and get GPU running at 16 on PCIEXT(G5)_1. To do that you only need NOT to connect anything on PCIEXT(G5)_2. It is what i have done and it is OK. see picture.

For the SSD speed i found a solution. I disabled the Intel VMD in UEFI (make some trouble thenafter to boot but the good way is to boot in safe mode). 

Now everything is OK : GPU at 16, all nvme at 4 (2xNVME SSD installed into Hyper M2 board and the board in PCIEX(G4).

Yours faithfully

[sl910 · Accepted solution]

Yes, you are right. The Intel 14900KF CPU can handle 20 PCie lines (version 4 or 5), i.e. x16-x4 or x8-x8-x4.

Yours sincerely