PCIx and SFP+

Deslok

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Jul 15, 2015
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Is anyone aware of a PCIx SFP+ networking card? I know it's an odd combo and I found these Lot 2 Napatech 810-0016-04 NetScout NT20X 2-Port 10Gbps PCI-X Network Adapter | eBay although I'm not sure if they'll actually work, apparently they're "capture cards"
And before I'm told to get a new server these are for my desktop Precision T7500, All my pcie slots are either in use or covered by the gpu so the options are fork out for a single slot gpu, or find a nic that can go in the pcix slot even if it's limited by the bus(pcix should drive 1 10GBe link depending on the version)
Or maybe I should get an XFP card and just do a short fiber patch instead of the direct attatch SFP+ cables I was going to use(and already have)?
 

PigLover

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Jan 26, 2011
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I don't know of such a card and I have serious doubts that it exists. You would have bandwidth issues supporting it (PCI-X 64bit could theoretically do 4.6GB/s, which is more than enough, but that was half-duplex speed and very few MBs supported it). You also have to consider the age - PCIe was widely available before 10Gbe SFP+ really started taking off (proposed 2006, standard published 2009) and any 10Gbe in the days of PCI-X would likely have been CX4 or XFP connectors rather than SFP+.
 

Deslok

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I saw those Napatech cards but they were called "capture cards" and I haven't found a ton of documentation for them otherwise.

Regarding the cards if I use a 10Gbase SR transceiver at each end does it matter if one is xfp and the other SFP+ they should be communicating via the same standard and be able to handle a direct system to system patch?(I only have 2 systems about 3' from each other I wanted to connect using 10GB and had initially planned to just use a pair of mellanox cards I had but without a very expensive gpu that's not happening)
 

Evan

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Jan 6, 2016
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XFP or SFP+ and the different connectors makes no difference, they connect just fine when you use the correct cable.
 

mstone

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I think the silent consensus is that this is a terrible idea. :) Single slot GPUs are a heck of a lot easier to find than PCIx cards in 2018, and you can probably get a single slot card < $50 that's faster than an 8 year old original card. Although, I am confused about why the dual slot GPU can't be positioned to block the PCI slot rather than a PCIe slot.
 

EffrafaxOfWug

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Feb 12, 2015
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Hmm I thought I'd written a response to this already but looks like it was gobbled by gremlins.

In a nutshell, yeah I don't think this is a very good idea. From the spec sheet, the T7500 uses a 64bit/100MHz PCI-X slot, so it won't be able to deliver the full 10Gb/s bandwidth if such a card existed. All of the cards I ever used myself used the obsolete CX4 connector, a quick google did show a fair few 10GbaseSR cards doing the rounds (as cesmith9999 has posted) but no SFP+ - since IIRC the SFP+ standard came in after PCIe became standard for everything.

Most of the blurb I've seen about those Napatech NT20X cards points to them being HBAs rather than NICs, and I think you'll find OS support a struggle. See also this post from a Reddit user who tried to do the same thing:
Repurposing an old packet capture device for Linux file server... 10Gb NIC problem. : linuxquestions
 

Deslok

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I think the silent consensus is that this is a terrible idea. :) Single slot GPUs are a heck of a lot easier to find than PCIx cards in 2018, and you can probably get a single slot card < $50 that's faster than an 8 year old original card. Although, I am confused about why the dual slot GPU can't be positioned to block the PCI slot rather than a PCIe slot.
simply it can't be moved because it's already been moved!
Top to bottom is
Sas 9201-16e
Samsung SM951NVME in m.2 adapter
USB 3.1 10GBPS dual host controller
EVGA 660Ti
(pci slot covered, I thought this was pcie so apparently a single slot gpu wont' help me after all)
PCIe interface card for AJA IO Express(I'm hoping to replace this with a different card for 4k captures eventually)
and the open PCI-x slot
Reduced_IMG_20181117_122131745.jpg
 

Deslok

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Hmm I thought I'd written a response to this already but looks like it was gobbled by gremlins.

In a nutshell, yeah I don't think this is a very good idea. From the spec sheet, the T7500 uses a 64bit/100MHz PCI-X slot, so it won't be able to deliver the full 10Gb/s bandwidth if such a card existed. All of the cards I ever used myself used the obsolete CX4 connector, a quick google did show a fair few 10GbaseSR cards doing the rounds (as cesmith9999 has posted) but no SFP+ - since IIRC the SFP+ standard came in after PCIe became standard for everything.

Most of the blurb I've seen about those Napatech NT20X cards points to them being HBAs rather than NICs, and I think you'll find OS support a struggle. See also this post from a Reddit user who tried to do the same thing:
Repurposing an old packet capture device for Linux file server... 10Gb NIC problem. : linuxquestions
I saw that same thread, I'm ok "only" getting 8GB/s(rough estimate of what 64/100 should deliver) since that's still 8x what I can get via gigabit. it looks like the 10GbaseSR cards are my answer since I can get a 10GbaseSR SFP+ for my other system and just use a small fiber patch instead of a twinax cable like I planed originally.
 

DanielWood

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Sep 14, 2018
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I was excited about this idea until I saw that it was more expensive than a 10Gbase SR pcix card XD
Is there enough clearance under the GPU hsf to put a Flex PCIe ribbon extension? If so, combine that with a PCIe 10Gb nic that is of the low profile variety and you have a solution that no one here would even bat an eye at.
 

Deslok

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Is there enough clearance under the GPU hsf to put a Flex PCIe ribbon extension? If so, combine that with a PCIe 10Gb nic that is of the low profile variety and you have a solution that no one here would even bat an eye at.
Not really, I actually checked while I was in the system and there's a PCI slot hidden there not PCIe like I thought it was. So a single slot gpu isn't going to help me after all unfortunately(not that I don't want one anyway... the RTX4000 looks fantastic...)