Question: USB card installations and risers, ribbons etc

[Bullwinkle]

My first server case is 2u (e.g. half height or low profile) and its expansion card back panel has card openings parallel to the mobo. So to install a good USB card I'll need to put a 90 degree angle riser or ribbon into the PCI express slot of my choice. (There is also the option of removing the back panel and replacing it with a panel with openings perpendicular to the mobo but I'm having trouble finding such a part so this would involve some heavy DIY.) 

 

The issue is as follows. It seems to me that all the good USB cards are PCI express 3.0 cards. Angle risers and/or ribbons that explicitly satisfy the 3.0 PCI standard seem to be scarce. (By explicitly I mean their makers explicitly tout them as PCI-e 3.0.) It's clear for instance that in Supermicro's listing of its risers, they make a clear and explicit distinction between the risers satisfying PCI-e 3.0 and those only satisfying PCI-e 2.0. In the case of Supermicro, they simply do not offer any angle riser that works for me.

 

If this issue actually matters it seems a shame to spend on an expensive PCI-e 3.0 card for better USB and then undermine its performance by botching the interface (by using a riser or ribbon that doesn't satisfy that standard).

 

The only feasible option I have found so far is a shielded ribbon cable made by Thermaltake that they explicitly tout as satisfying PCI-e 3.0. It is not cheap, $37 on ebay, although this pales in comparison to the price of most of the USB cards we're talking about, so perhaps I shouldn't whine about it.

 

At any rate I wonder whether anyone else has confronted this particular issue and how they resolved it. Anyone else using a ribbon or angle riser to install their fancy USB card? Did you even worry about whether your solution explicitly satisfies PCI-e 3.0? Am I worrying about a nothingburger?

 

Thanks for any wisdom.

[Bullwinkle]

FYI, the issue is not a nothingburger. See this interesting and informative post, a fair warning:

 

https://www.computeraudiophile.com/forums/topic/31499-riser-cable-for-sotm-defect/

 

[ElviaCaprice]

Which PCIe audiophile usb cards require a 3.0 slot?  All the ones I've seen are 1x.

[Bullwinkle]

@ElviaCaprice If you are right, then my particular issue is a nothingburger; but @bluesfendermanblues might still have a point--that some of the riser/ribbon solutions are flaky.

 

I've been acting under the assumption that the PPA v1 I recently acquired was pci express 3.0 (though it obviously uses only one lane). If that's not true, sorry for the bum steer.

[rickca]

25 minutes ago, ElviaCaprice said:

Which PCIe audiophile usb cards require a 3.0 slot?  All the ones I've seen are 1x.

You are confusing the standards specification (PCI-E 2.0, PCI-E 3.0) with the connection bandwidth (x1, x4, x8, x16).

[Bullwinkle]

I'm pretty certain that (for instance) the Jcat Femto must be at least pci express 2.0. Otherwise there's no way it could have a top rate of 5 Gbps (as claimed on Jcat's website). See the Wikipedia table in this entry:

 

https://en.wikipedia.org/wiki/PCI_Express#PCI_Express_3.0

[ElviaCaprice]

14 minutes ago, rickca said:

You are confusing the standards specification (PCI-E 2.0, PCI-E 3.0) with the connection bandwidth (x1, x4, x16).

Whoops, your right.  But that old version 1 PPA card will work in PCIe 2.0 or 3.0 and you only need a X1 slot.  I don't understand your big concern about riser cards?  Just because one didn't work for someone doesn't mean they are all bad.  All 3.0 should be backward compatible.  If you have a half height expansion slot vertical, use that.

[Bullwinkle]

Hi @ElviaCaprice, I put out feelers to both Jplay and PPA. Will report back...

[Bullwinkle]

Paul Pang replies that the PPA usb v1 is pci express standard 2.0. I didn't get a straight answer from the Jplay folks... they simply said it is compatible with 1.0, 2.0 and 3.0, and that I would be delighted, but would not say which standard is needed to enjoy the full abilities of the usb femto. I think we can infer (from claims Jplay makes for the card's speed) that it must be at least pci express standard 2.0.

 

Yum, this crow is tasty.

[Marcin_gps]

On 5.05.2017 at 11:35 AM, Bullwinkle said:

Paul Pang replies that the PPA usb v1 is pci express standard 2.0. I didn't get a straight answer from the Jplay folks... they simply said it is compatible with 1.0, 2.0 and 3.0, and that I would be delighted, but would not say which standard is needed to enjoy the full abilities of the usb femto. I think we can infer (from claims Jplay makes for the card's speed) that it must be at least pci express standard 2.0.

 

Yum, this crow is tasty.

 

To be exact: the µPD720201 controller used on the JCAT USB Card FEMTO is compatible with the USB 3.0 and xHCI (eXtensible Host Controller Interface) 1.0 specifications. The system bus is compatible with the PCIe Gen2 specification.

 

However PCIe Gen2 devices are backwards compatible, so you should have no problems in PCIe Gen1 slot. The hardware will only function at PCI-E 1.0 speeds though. 

 

Cheers, 
Marcin