PCIE 4.0 16x Host/Target adapter

[DRW]

Pardon Our Interruption...

Kind-of a crazy deal for these if you have a use for them, with decent discounts for 4+.

PCIe Gen4 x16 SFF-8644 Host Card with Microchip Switchtec PCIe Switch | Gen4 PCIe

serialcables.com

Configurable via dip-switches and usb CLI.
I'm a bit salty that these are so cheap, given I paid a *lot* more for a few of the OSS version of these a couple years ago (though the OSS cards support fiber connectors and these don't).

So obviously I bought a bunch of these out of pure cope and spite.

Supposedly these are rated for up to 3m cables. Ideally, I'd like to use them in host/passive mode (no target card - directly out to a nvme backplane), with a shorter cable if necessary. If that's not viable, it's a bit of a problem considering that (I believe) the target card needs to be signal-swapped at the edge connector (I'm not an expert though). There is a company that sells signal-swapped pcie riser cables (though they aren't cheap). I might try rigging something up with a signal-swap cable connected to a powered pcie cable connected to a passive/switchless breakout board. Doesn't sound too great for signal integrity though.

I know there are other people around here interested in this stuff. Hopefully this is one step closer to my dream of a semi-diy Liqid-like system.

 

[Koop]

What kind of cables do you use with these? SFF-8644 to ?

Could you explain some use cases of stuff you'd connect to this externally? I could fathom some ideas but I'm curious what it was designed for?

I'm trying to imagine a way to connect a bunch of NVMe storage somehow. It's the whole external part that I'm all unsure about. Not like it's all too easy to come across enclosures for a bunch of NVMe?

 

[DRW]

What kind of cables do you use with these? SFF-8644 to ?

Could you explain some use cases of stuff you'd connect to this externally? I could fathom some ideas but I'm curious what it was designed for?

I'm trying to imagine a way to connect a bunch of NVMe storage somehow. It's the whole external part that I'm all unsure about. Not like it's all too easy to come across enclosures for a bunch of NVMe?

Yeah they (serial cables) sell jbof enclosures for u.2 nvme. SFF-8644 to SFF-8644. None of this stuff is exactly common.

I have a 2u supermicro chassis that I've stuck a 24 slot direct-attach u.2 nvme backplane into. My dream is to connect multiple compute nodes to the same jbof via SFF-8644 to SFF-8643 passthrough directly to the backplane, and maybe have a couple of gpus in there too if I can. Basically move a bunch of heat, power, and cables to it's own dedicated enclosure.

 

[mattventura]

I have a thread where I bought a couple of these (version 1.1 and 1.2): https://forums.servethehome.com/ind...ith-serialcables-com-pci4-ad-x16he-bg4.47497/

What was news to me is that the SFF-8644 pinout seems to be less standardized than I had thought. Seems that some devices such as this one have the lanes in the order 0-3-1-2, while others use 1-3-0-2. I'd love to know what sorts of enclosures and such will work with this without needing proprietary cables.

 

[DRW]

I have a thread where I bought a couple of these (version 1.1 and 1.2): https://forums.servethehome.com/ind...ith-serialcables-com-pci4-ad-x16he-bg4.47497/

What was news to me is that the SFF-8644 pinout seems to be less standardized than I had thought. Seems that some devices such as this one have the lanes in the order 0-3-1-2, while others use 1-3-0-2. I'd love to know what sorts of enclosures and such will work with this without needing proprietary cables.

Good to know. I must have missed that thread. Might be some caveats then to this deal. In host/target mode, the cable pinout should be irrelevant though. Though that introduces other expenses.

 

[doop]

Will this work in a x8 slot? My motherboard can split the GPU into two x8 slots (x16 wide physical). Can I use this to connect up to 8 NVMEs thru the x8 slot?

 

[DRW]

Will this work in a x8 slot? My motherboard can split the GPU into two x8 slots (x16 wide physical). Can I use this to connect up to 8 NVMEs thru the x8 slot?

I don't think this supports splitting down to 1x lane per port. You are probably better off with something like this for that use case: Pardon Our Interruption... (I have no experience with it though; other threads already exist discussing it).

 

[mattventura]

It supposedly does support 8x2 downstream, but I haven't tried that, and I'm not sure what cable you would need.

 

[DRW]

It supposedly does support 8x2 downstream, but I haven't tried that, and I'm not sure what cable you would need.

Unless I misunderstood, I think that poster wants his 8x split out to 1x1x1x1x1x1x1x1x.

 

[mattventura]

Unless I misunderstood, I think that poster wants his 8x split out to 1x1x1x1x1x1x1x1x.

Since it's a switch, the upstream port width doesn't matter for the downstream ports except that it would bottleneck. You could plug it into a x1 upstream port and still have 1x16, 8x2, or whatever downstream.

 

[DRW]

Since it's a switch, the upstream port width doesn't matter for the downstream ports except that it would bottleneck. You could plug it into a x1 upstream port and still have 1x16, 8x2, or whatever downstream.

Oh gotcha, I see what you are saying.

 

[luckylinux]

I just bought a few Dell KVXGG (Dolphin MXH932), which is a Microchip-based PCIe 4.0 x16 Transparent Host / Target Adapter.

It was a bit cheaper than the PCIe Adapter mentioned in the Title of this Thread and Seller countered with an Offer of 5 Pieces x 45 USD / Piece (instead of list Price of 58.90 USD).

Similar listings from other Sellers (I bought all of those that another Seller had ):

Pardon Our Interruption...

Pardon Our Interruption...

Now as @mattventura mentioned, I'm also wondering how the Pinout of SFF-8644 Cables is and if I could just buy any SFF-8644 Cable which is 0.5m - 0.6m long, such as e.g.:

Dell Mini SAS Kabel SFF-8644 / SFF-8644 0.5m 0WTCFX - Piospartslap

Dell Dell Mini SAS Kabel SFF-8644 / SFF-8644 0 5m P/N: 0WTCFX Technical data / Technische Daten Manufacturer / Hersteller Dell Type / Gerä

www.piospartslap.de

I'm not sure however if it really matters, shouldn't both ends of the Cable be in the same Way ? It's not supposed to be a "crossover" Cable, right ?

 

[mattventura]

I just bought a few Dell KVXGG (Dolphin MXH932), which is a Microchip-based PCIe 4.0 x16 Transparent Host / Target Adapter.

It was a bit cheaper than the PCIe Adapter mentioned in the Title of this Thread and Seller countered with an Offer of 5 Pieces x 45 USD / Piece (instead of list Price of 58.90 USD).

Similar listings from other Sellers (I bought all of those that another Seller had ):

Pardon Our Interruption...

Pardon Our Interruption...

Now as @mattventura mentioned, I'm also wondering how the Pinout of SFF-8644 Cables is and if I could just buy any SFF-8644 Cable which is 0.5m - 0.6m long, such as e.g.:

Dell Mini SAS Kabel SFF-8644 / SFF-8644 0.5m 0WTCFX - Piospartslap

Dell Dell Mini SAS Kabel SFF-8644 / SFF-8644 0 5m P/N: 0WTCFX Technical data / Technische Daten Manufacturer / Hersteller Dell Type / Gerä

www.piospartslap.de

I'm not sure however if it really matters, shouldn't both ends of the Cable be in the same Way ? It's not supposed to be a "crossover" Cable, right ?

I'm not 100% sure, but I think it's that the data pairs aren't necessarily mapped the same on each ends (e.g. tx0 might match up to rx1 on the other end instead of tx0 -> rx0 as expected).

 

[luckylinux]

I'm not 100% sure, but I think it's that the data pairs aren't necessarily mapped the same on each ends (e.g. tx0 might match up to rx1 on the other end instead of tx0 -> rx0 as expected).

You mean that's what some OEM Cables (e.g. Dell) possibly do ?

 

[luckylinux]

Of course the 5 Pieces I thought I bought ... Well, the Seller just noticed that they shipped 2 or 3 Pieces only and have no more left in Stock now .

 

[luckylinux]

Just bought another 6 Pieces of Serial Cables for 45 USD each.

I wonder if I should buy a few more in order to have a pair of Host + Target, although it's not fully clear if standard Cables can be used with a special Configuration Setting.