Combine PCIE ports for Raid 0 card (reverse Bifurcation)

[crazycraig]

I want to combine two pcie x8 ports to run my Asus hyper m.2 card with all 4 m.2 drives as raid 0. My board has 2 x16 slots and 2 x8 slots (asus prime board) workstation use

running 2 gpu, I considered that it MAY be possible to run hardware 16x into two x8 splitter, with two x8 riser cables essentially running the whole thing in reverse, obviously i would need to

rewire one of the x8 ports to use the last set of pins in the x16 socket, and get or make the female to female cable to give me back a female socket to plug the hyper m.2 card into. Obviously

this would not work for a gpu, but as the hyper m.2 card will work in x4,x4,x4,x4 mode on AMD chipset boards, and the prime board I have allows raid across any drives available, I wonder if this would work ok

 

Any thoughts, are there any hardware options that can already do this?

 

thanks

[Kilrah]

No. What board exactly?

 

If it really does have 2 X8s AND supports bifurcating them (both seem surprising) you could use 2 hyper m.2s or siimilar and use 2 drives on each.

[OddOod]

Welcome to the forums!
This is not a thing that is done. I imagine that it's party because of PCIe spec, and partly because anyone who would need to merge two 8x slots, would normally just get a mobo that had the necessary number of slots. 
Also, why would you want 4 drive nvme raid 0? What possible use is there for that in the consumer space?

[crazycraig]

Asus Prime x299 deluxe II , running xeon 2255, 192gb ram (quad channel 256gb supported), Dual 2080ti, As i said its a graphics WS, and yes it has 2 x16 2x8 and 2 x1 pcie, and 2 onboard m.2 slots

I have enough lanes to run the two 2080's and the hyper m.2, the problem is that the board layout is x1, x16 then x8 then x16,  x1 and x8, so the upper x8 slot is covered by the first GPU, meaning i will have to use a riser cable to get access to it, and if i only use the x8 slot at the bottom then only 2 of the four m.2 can be available for raid.

The reason I want the 4 m.2 is for the transfer rate, for video editing etc, plus the storage, currently holding about 5tb of files across 3 HDD, so would like to consolidate all that into a single drive, which will last me a few more years. I realize how old the system is, but considering I cant get anything near the specs of this one for a reasonable price, and the failure rate of the new 14th gen cpu's I cant see the point in updating, as it would also cost me in RAM capacity 128gb Dual channel vs 196gb in Quad channel now. I had considered switching to a single GPU but then I would have a bottleneck in the PCIE bus effectively limiting the new GPU to about half its actual perfomance so not much point as it may be slower than the dual 2080's now

[freeagent]

On 9/17/2024 at 5:24 AM, crazycraig said:

I want to combine two pcie x8 ports to run my Asus hyper m.2 card with all 4 m.2 drives as raid 0.

Cantt be done. It needs a full x16 slot, and you would have to use iGPU.

[igormp]

10 hours ago, crazycraig said:

and the failure rate of the new 14th gen cpu's

Well, AMD is a thing as well.

10 hours ago, crazycraig said:

as it would also cost me in RAM capacity 128gb Dual channel vs 196gb in Quad channel now

You can have 192GB on consumer platforms with 4x48GB sticks. Your bandwidth is going to be a bit worse, but should still be able to reach 80~90GB/s (which is pretty close to the max of that setup of yours in quad channel).

10 hours ago, crazycraig said:

a single GPU but then I would have a bottleneck in the PCIE bus effectively limiting the new GPU to about half its actual perfomance so not much point as it may be slower than the dual 2080's now

What kind of workloads are you dealing with? Are you sure it's that intensive on PCIe transfers for that to be the case?

10 hours ago, crazycraig said:

The reason I want the 4 m.2 is for the transfer rate, for video editing etc, plus the storage, currently holding about 5tb of files across 3 HDD, so would like to consolidate all that into a single drive

You could go with two 4TB NVMes, or just a single 8TB one. More than enough storage and less risks of things breaking with a 4x raid 0 setup.

Are you already making use of all available NVMe slots?

10 hours ago, crazycraig said:

and 2 onboard m.2 slots

Seems like it has 3, with 2 form the chipset and one from the CPU lanes:

 

11 hours ago, crazycraig said:

I have enough lanes to run the two 2080's and the hyper m.2, the problem is that the board layout is x1, x16 then x8 then x16,  x1 and x8, so the upper x8 slot is covered by the first GPU, meaning i will have to use a riser cable to get access to it, and if i only use the x8 slot at the bottom then only 2 of the four m.2 can be available for raid.

The way you said makes it a bit confusing, so I took a look at the manual:

I believe what you're saying is that you have your GPUs in the slot no. 1 and 3, right? The slot #5 gets limited to x8 only, and if you wanted to put a GPU in there you'd need a riser. Long shot, but is it possible to bifurfate that slot 5 into a x2/x2/x2/x2 config? If so, you could use 4 NVMes at half speed each still.

 

However, that mobo goes against what you said earlier:

On 9/17/2024 at 7:24 AM, crazycraig said:

My board has 2 x16 slots and 2 x8 slots

I only see 2 x16 and ONE x8 slot.

 

 

One other option would be to give up on the Hyper idea, since it's just a dumb lane splitter, and get a card with an actual PCIe switch so you can have 4 or more NVMes onto a single x8 slot without issues.

[crazycraig]

yeah sorry its the x299 deluxe not the mark II, so the "B" m.2 socket is actually an x16 size socket

but only has half the connectors in it same as the bottom x8. As i mentioned earlier, the hyper m.2 card

will run on an AMD system at x8, x8 or x4,x4,x4,x4 using bifurcation, so assuming i get the riser setup

correct, combining the two x8 sockets, would be like me "cutting the hyper m.2 in half" and running half in each

of the x8 slots, the VROC then combines the drives back into the array, with all drives using CPU lanes instead of

the chipset