Connecting U.3 NVMe to PCIe

[tubs-ffm]

Hello,
I want to connect two U.3 NVMe (SFF-8639) to the PCIe slot in my home server. But I cannot decide on the adapter solution to go with.

Option A: (PCIe to SFF-8639)
Using an adapter where the U.3 device is mounted directly on the adaptor in the same way as people usually do with M.2 devices.
Advantage: Less electrical interfaces and shorter electrical distance could be more robust.

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Example: DeLock 90162​

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Option B: (PCIe to SFF-8654/SFF-8643)
Using an adapter that provides a connector and connecting the U.3 devices via cable to it.
There are adapters with SFF-8654 and SFF-8643 connection. I do not know which one will be better.
Advantage: Could locate the U.3 devices in the drive bay behind the fans with better cooling.

Example: DeLock 90076 with SFF-8654​

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Any recommendations or thoughts?

PS: The need for bifucuration for both solutions is clear to me.

 

[pimposh]

Unless it is absolutely necessary, don't use cabling.
Proper backplanes have retimers; cables are passive, so you may encounter disconnection issues, etc.

 

[jode]

Hello,
I want to connect two U.3 NVMe (SFF-8639) to the PCIe slot in my home server. But I cannot decide on the adapter solution to go with.

Option A: (PCIe to SFF-8639)
Option B: (PCIe to SFF-8654/SFF-8643)

Any recommendations or thoughts?

Both options work pretty reliably on PCIe Gen3 signaling. Faster/newer connections are significantly more challenging. Depending on your mobo you may need a retimer card (e.g. https://www.amazon.com/gp/product/B0DP27F2K7) for successful connectivity.

 

[tubs-ffm]

Both options work pretty reliably on PCIe Gen3 signaling. Faster/newer connections are significantly more challenging.

Thank you.
My board (Supermicro X10SRH-CLN4F) is an old PCIe 3.0.But In am planning to use PCIe 4.0 drives.
Looking to the future, I assume the drives will outlive the board and a solution that also works with PCIe 4.0 I will prefer.

Depending on your mobo you may need a retimer card (e.g. https://www.amazon.com/gp/product/B0DP27F2K7) for successful connectivity.

I assume this retimer is needed in case of more than one drive should be used and the board does not support bifucuration.
Or does it have another function?

 

[unwind-protect]

It depends on what you can cool easier in your particular setup.

I use the in-PCIe-slot card option with a fan pointed at them.

What I'd really want is a hotswap frame like this: https://www.amazon.com/ICY-DOCK-ToughArmor-Rugged-External/dp/B07B9HK4QG/ref=sr_1_3
But as people pointed out - more components, more opportunity for breakage. And the fans might be loud.

 

[tubs-ffm]

It depends on what you can cool easier in your particular setup.

Easier to cool for me are the drives bays behind the front fans in my tower housing.
But another M.2 NVMe feels ok at one of my PCIe slots.

I use the in-PCIe-slot card option with a fan pointed at them.

Additional fan I want to avoid due to noise. That's why I have an oversized housing with slow running big diameter fans.

What I'd really want is a hotswap frame like this: https://www.amazon.com/ICY-DOCK-ToughArmor-Rugged-External/dp/B07B9HK4QG/ref=sr_1_3

Hot swap I do not need at all.
But using a cage with backplane instead of cables with SFF-8639 and SATA power in I was thinking about. I only could not find something like this.

 

[mattventura]

The card option is usually easier to cool since the drives are exposed to the normal airflow within the case. You don't need tons of airflow, but you do need some. The enclosures like the one linked above tend to have 40mm fans which are quite noisy.

 

[tubs-ffm]

I see. I was leading in the wrong direction.

An enclosure never was the plan. I cam up with this because of the backplane as potential option to single cables.
The options are free vented behind the front fans like the other HDDs or free vented on the adaper card on the PCIe slot where less air flow is.