EPYC3251D4I-2T - PCIe Bifurcation

dawidwozny

New Member
Nov 22, 2021
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I would like to create nvme based storage using EPYC3251D4I-2T. The motherboard has single x16 PCIe slot and I would like to attach ASUS Hyper M.2 x16 to it which gives me 4 extra nvme slots. This setup requires PCIe bifurcation.

I can’t find in manual neither in the internet. Does this motherboard support PCIe bifurcation?

There is nothing obvious on manual but I belive this functionality can be hidden under width option.

1637616678583.png
 

RolloZ170

Active Member
Apr 24, 2016
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ask ASRock Rack support for a custom BIOS.
if they don't have your only chance is the IO Crest SI-PEX40157 or similar.
 

dawidwozny

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Nov 22, 2021
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Thanks for the reply. I sent it now. Waiting for response. I have seen people building NAS based on this motherboard on this forum. Thought somebody know it already. The setups were more focused on hdd/sata ssd though.
 

dawidwozny

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Nov 22, 2021
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This oculink will give me just one nvme. You need x4 lanes per one nvme drive. Sata is slower so you can have 4 sata ports. I want at least 4 nvme-s. If there is support for bifurcation I will be able to have 6. 1 native, 1 from oculink, 4 from hyper m2.

1637620488633.png
 

RolloZ170

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Apr 24, 2016
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ooh i see. the manual is shared for many different motherboards. one variant(SP4 SKU) supports 3 Oculinks, with the M.2 there where four.
 

dawidwozny

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Nov 22, 2021
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Yeah, I can't really work out which MB is this SP4 SKU but I assume it is the one without 10Gbe network card so it is no go. I have almost believed this could work :)
 

nasi

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Feb 25, 2020
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IIRC the other option for "PCIE7 link width" is indeed x4x4x4x4. But since my board is running 24/7 I can't have another look into it soon.
 

RolloZ170

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Apr 24, 2016
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IIRC the other option for "PCIE7 link width" is indeed x4x4x4x4. But since my board is running 24/7 I can't have another look into it soon.
very good idea, should be mine....
you are right:

EPYD42T1.20.jpgEPYD42T1.20
 

dawidwozny

New Member
Nov 22, 2021
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@nasi Thanks. I think yours IIRC should be enough for me to take the risk. This motherboard tick all the boxes for me.
@RolloZ170 What is the program you are using? I presume you have different motherboard since I can see multiple oculinks.
 

RolloZ170

Active Member
Apr 24, 2016
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What is the program you are using? I presume you have different motherboard since I can see multiple oculinks.
AMIBCP
with this tool you see ALL, even the Hidden settings you never see in your BIOS
all variants share one BIOS, this is your BIOS 1.20 from the ASRock site.

with this Tool you can set i.e. the default bifurcation to 4x4x4x4 instead of x16.
but you can use Instant flash only, not the IPMI flash function because it checks a checksum.
 
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