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PCI Express over Fiber [video]
- dyheueiigd 6mo ago[flagged]
- mmastrac 6mo agoThis was a super interesting video to watch. I honestly thought SFP required more setup, but this explains why AliExpress is so ripe with USB3 and HDMI over SFP converters that are dirt cheap.
- jauntywundrkind 6mo agoIt's been amazing having 6 years of fiber optic HDMI & DP monitor connections, that work so so so well. I bought some no name one on Amazon in ~2019 and was flabbergasted it was real & worked. Such a huge upgrade from the heavy thick 35 ft HDMI<->dvi cable I've used for so long. Literally the only downside is figuring out how to roll it up, which I still haven't figured out how to do well with the 150ft cable I have. It was astoundingly cheap too. I think the first one I got was under $60?! No one really knew the segment existed, they just needed to get some sales, I assume. I heard usb3 has been available but they've been bulky & expensive. Where-as the whole fiber optic cable seamlessly integrates the transceiver on mine. I like Cable Matters, they make some fine ones.
- fl4regun 6mo agoCool project! PCIe itself I think is likely to end up doing something similar soon, there are provisions in the spec now for optical retimers.
- russdill 6mo agoThere's a number of optical modules for TB3 and TB4, might be an easier (but less fun) route as TB3 and TB4 can carry PCIe.
- deleted 6mo ago[deleted]
- whalesalad 6mo agoSo you're saying I can put a handful of 4090's out in the middle of snowy Michigan with a handful of OM4 cables snaking into my basement to run legit arctic cooling with no noise?
- phendrenad2 6mo agoWatercooling loop light be better, the radiator fins will still rust from condensation.
- preisschild 6mo agoMight as well put your entire computer outside and use thunderbolt/usb-4 over fiber docks
- benjojo12 6mo agoI mean yes, but you could also just place the entire computer out there as well
- myself248 6mo agoNo part of Michigan is in the arctic, but sure, outside of mosquito season, that would work.
- throwaway270925 6mo agoBetter yet, keep it inside and save big on heating!
- greenavocado 6mo agoWhat you meant is you will have your GPU rig running passively cooled inside the pond tethered to your pier in your back yard
- buildbot 6mo agoBlog post for people who prefer reading: https://hackaday.com/2026/04/11/implementing-pcie-over-fiber-using-sfp-modules/ https://hackaday.com/2026/04/11/implementing-pcie-over-fiber... While at a higher level, thunderbolt and https://en.wikipedia.org/wiki/ExpEther https://en.wikipedia.org/wiki/ExpEther can both of course work over fiber too! (Q|O)SFP are basically just raw high speed serial interfaces to whatever - you see this a lot in FPGAs, you can use the QSFP interfaces for anything high speed - PCIe, SATA, HDMI…
- dcrazy 6mo ago> Although we can already buy commercial transceiver solutions that allow us to use PCIe devices like GPUs outside of a PC, these use an encapsulating protocol like Thunderbolt rather than straight PCIe. > [snip] > As explained in the intro, this doesn’t come without a host of compatibility issues, least of all PCIe device detection, side-channel clocking and for PCIe Gen 3 its equalization training feature that falls flat if you try to send it over an SFP link. So, uh… what’s the benefit? How much overhead does Thunderbolt really introduce, given it solves these other issues?
- jmyeet 6mo agoThe benefits are twofold: physical colocation and bandwidth. Thunderbolt 5 offers 80Gbps of bidirectional bandwidth. PCIe 5.0 16x offers 1024Gbps of bidirectional bandwidth. This matters. TB5 cables can only get so long whereas fiber can go much farther more easily. This means that in a data center type environment, you could virtualize your GPUs and attach them as necessary, putting them in a separate bank (probably on the same rack).
- mikepurvis 6mo ago"same rack" should still be fine for 1m passive TB5 cable though, right?
- consp 6mo ago> 1024Gbps Good luck getting a 1Tbit tranceiver. Anydirectional. Also it's 512Gbitish per direction.
- ahepp 6mo agoHow does this compare to something like RDMA over Converged Ethernet (RoCE)?
- KeplerBoy 6mo agoIt seems rather educational.
- pncnmnp 6mo agoA fun tangent - if someone wants to explore how Azure is performing RDMA over RoCEv2 - check this paper out - https://www.microsoft.com/en-us/research/wp-content/uploads/2023/03/RDMA_Experience_Paper_TR-1.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/... There is an interesting NSDI talk on the paper too - https://www.youtube.com/watch?v=kDJHA7TNtDk https://www.youtube.com/watch?v=kDJHA7TNtDk (2023)
- system2 6mo agoI love the Neon Genesis background, awesome project too.
- ecshafer 6mo agoThe neon genesis background plus this awesome technical breakdown feels so early 2000s.
- jauntywundrkind 6mo agoAmusingly PCIe is talking CopprLink now, which is amusing because it also the expected basis for future optical work (yet has coppr in the name). I'm honestly not sure what if anything it brings vs OCuLink, if relaxes timings at all/allows latency, or if it's just specifying connectors etc. https://pcisig.com/blog/pcie%C2%AE-cabling-%E2%80%93-journey-copprlink%E2%84%A2 https://pcisig.com/blog/pcie%C2%AE-cabling-%E2%80%93-journey... https://www.tomshardware.com/pc-components/gpus/copprlink-destroys-every-egpu-standard-in-new-test-achieves-near-native-level-performance-with-an-rtx-5090-setup-requires-usd2-300-worth-of-additional-hardware https://www.tomshardware.com/pc-components/gpus/copprlink-de... Worth noting too that well respected vendors have been selling optical thunderbolt cables for a while now. I wonder if they are length limited for latency reasons (& hello hollow core fiber)? I wonder if they are usb3/multiprotocol, or if they are usb4 only. I also wonder how they handle the incredibly jank usb4 requirement to also have a separate legacy usb2. As a usb-c enjoyer, I can still admit: sure seems like USB is a lot of work to support! I can't help but wonder how blissfully simple a future CXL over cable stack might look by compare. https://www.owc.com/solutions/usb4-cables https://www.owc.com/solutions/usb4-cables
- felixfurtak 6mo agoNothing new here. Samtec were doing this in 2017 https://www.samtec.com/support/videos/pcie-over-fiber-with-firefly-ofc-2017-samtec-210783964/ https://www.samtec.com/support/videos/pcie-over-fiber-with-f...
- parl_match 6mo agoand consumer/prosumer pcie encapsulation over thunderbolt over fiber was happening in 2015. maybe even earlier still, it's incredibly cool for one guy to pull this off on his own. demonstrates mastery of the subject
- ktm5j 6mo agoDoes it have to be new?