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Free interactive tool that shows you how PCIe lanes work on motherboards
- sidewndr46 11mo agoWow, this is great! I don't know how they generate this but it's really impressive. One of the things that I've been surprised with is some older dual socket workstations have tons of PCI-E lanes, but none are hooked to the second CPU it seems
- nirav72 11mo agoNice! One suggestion - please add AM4 socket boards. With current memory prices, AM5 with DDR5 is becoming unattainable for some. DDR4 prices are rising as well. But not nearly as bad as DDR5.
- Dylan16807 11mo agoSo you're specifically considering the people that would have gone AM5 but are now looking at AM4 at the end of 2025 and into 2026? Is that a significant number of people? I kind of expect almost everyone that waited this long to sit tight on their current builds and keep waiting until RAM goes back down.
- dontlaugh 11mo agoSome don’t already have a build. AM4 has high end gaming CPUs available and there are not yet major limitations besides future upgrades. AM4 parts probably makes the best value gaming build you can get right now.
- Dylan16807 11mo ago> Some don’t already have a build. The number of people that don't have a previous computer and are shopping based on individual parts is even smaller. > AM4 parts probably makes the best value gaming build you can get right now. Has the value improved in the last year and a half? The people that would want AM4 have had a long time to buy AM4.
- dontlaugh 11mo agoYes, due to DDR5 prices going up after a period of people upgrading to AM5. There is currently a lot of second hand AM4 DDR4 stock, making the value particularly good. FWIW I recently upgraded and ended up getting something else, but mostly due to lack of availability of ITX AM4 motherboards. I got one with a soldered high end laptop CPU, it was much cheaper.
- Dylan16807 11mo agoDDR5 price increases don't make AM4 improve, they just make AM5 worse. Consistent drops from secondhand stock sound good.
- dontlaugh 11mo agoIt makes AM5 less attractive and AM4 better value relatively. This situation will end eventually, of course.
- gr4vityWall 11mo ago> Has the value improved in the last year and a half? I'd say yes, my reasoning being: 1. DDR5 got more expensive; 2. 16 cores AM4 CPUs are cheaper, partially due to the release of the 5900XT (16C/32T CPU, basically a rebranded 5950X with 100mhz lower single-core boost clock); 3. Lots of gamers selling their used AM4 kits for good prices as they migrate to the 9800X3D.
- KronisLV 11mo agoIf I needed a new build right now, it would most likely be AM4. Going for the latest gen would just be out of my price point, whereas AM4 still has plenty of good chips and motherboards out there.
- NedCode 11mo agoLegendary!
- asciii 11mo agoWarning: addicting site :)
- rao-v 11mo agoI’ve been struggling to find an AM5 board that can run three MI50s at 4x. This is perfect thank you. Him are you sure about some of the PCI slots? I think some marked as 4x get downgraded to 1x on these boards… Further edit - this maybe accurate - how are you getting this / confirming it?
- chainingsolid 11mo agoI would normally figure this out by reading motherboard manuals. Which for SKUs you can buy standalone tend to be on the manufacter's site with no account/paywall. They tend to include all the "if you populate this slot you lose xyz" language. Along with how to change PCIe lane bifercation in bios if nessesary.
- Will-Reppeto 11mo ago[flagged]
- smcleod 11mo agoThat is so incredibly useful, hardware vendors do such a bad job of properly advertising how many GPUs will actually work and with what combination of m.2 slots in use.
- consp 11mo agoBifurcation support is also almost never mentioned, even if the bios supports it.
- SketchySeaBeast 11mo agoYup. I've been lost for a while on how to properly set up my MSI X870 TOMAHAWK mobo, this makes it all clear. Boy is it a mess with all the bifurcation.
- _9vpl 11mo agoVery nice! Just a note (as the site says on bottom left side), this can vary depending on the CPU you use, would be nice to be able to select all different variations of supported CPUs as a future feature.
- tagyro 11mo agoFor disclosure, this was created by "Ronin Wilde" - https://www.youtube.com/watch?v=cgdXj75VSMo https://www.youtube.com/watch?v=cgdXj75VSMo I found it useful and thought others might also like it.
- throw7 11mo agoI wish all manufacturers clearly gave info like this up front. AM4 boards would be nice.
- PunchyHamster 11mo agoYeah my ASRock have nice map of the every lane and interface and where they are connected on the board. Especially important as some devices go thru second io expander
- matja 11mo agoHow can I contribute the data for the boards I own which are not on the site?
- gitpusher 11mo agoWhoa. This is so cool and helpful. Too bad my board is Intel. Is there a way to contribute to this?
- tagyro 11mo agoI dropped a message to the creator :fingers_crossed: they open the motherboard database so we can make contributions
- rkagerer 11mo agoCan anyone recommend a specific, well-made, high-performance motherboard with loads of PCIe lanes and expansion slots, and sensible lane topology? All the motherboards these days make me feel claustrophobic. My current workstation is pretty old, but feels like it had more expansion capability (relative to its time) than what's on the market today.
- rkagerer 11mo agoSome builds I kept tabs on: Let's Encrypt documented their early 2021 whitebox that used 128 PCIe 4.0 lanes, mainly for storage: https://letsencrypt.org/2021/01/21/next-gen-database-servers.html https://letsencrypt.org/2021/01/21/next-gen-database-servers... Troy Hunt (HaveIBeenPwned) recently solicited upgrade advice from the internet and settled on an Asus Pro WS TRX50-SAGE WIFI (which doesn't appear to be in the MoboMaps database yet): https://gist.github.com/troyhunt/a6e565981e4769976e9cffb705f6cca0 https://gist.github.com/troyhunt/a6e565981e4769976e9cffb705f...
- Aurornis 11mo agoYou’ll have to be more specific about your price range. There are a lot of server and workstation chipsets/platforms that will have a large number of PCIe lanes, but you will pay for them. I really suggest not seeking a lot of PCIe lanes unless you really need them right now, though. The price premium for a platform with a lot of extra PCIe is very steep once you get past consumer boards. It would be a shame to spend a huge premium on a server board and settle for slower older tech CPUs only to have all of those slots sit empty. It’s a good idea to add up the PCIe devices you will use and the actual bandwidth they need. You lose very little by running a GPU in a PCIe x8 slot instead of a full x16 slot, for example. A 10G Ethernet card only needs 1 lane of PCIe 4.0. Even fast SSDs can get away with half of their lanes and you’ll never notice except in rare cases of sustained large file transfers.
- shadowpho 11mo ago>Even fast SSDs can get away with half of their lanes and you’ll never notice except in rare cases of sustained large file transfers Sorta yes but kinda the other way around — you’ll mostly notice in short high burst of I/O. This is mostly the case for people who use them to run remote mounted VM. Nowadays all nvme have a cache on board (ddr3 memory is common), which is how they manage to keep up with high speed. However once you exhaust the cache speeds drop dramatically. But your point is valid that very few people actually notice a difference
- temp0826 11mo agoProbably a good thing SLI fell out of fashion. No consumer boards with multiple 16x, but a few with 2 8x (gated behind a "mode" switch). A few years ago it was looking like we were on our way to full 4 16x slots. For cuda/llm/whatever does it really matter if the cards are in 1x slots?
- hoss1474489 11mo agoGPUs in 16x slots is still important for LLM stuff, especially multi-GPU, where lots of data needs to move between cards during computation.
- Dylan16807 11mo agoDepends on what you're doing. I'm pretty sure the bandwidth for inference isn't much.
- eurekin 11mo agoDepends, if it's tensor parallel or pipeline parallel. Only PP doesn't pass too much. TP does
- __alexs 11mo agoA 16x PCIE 6.0 setup has more bandwidth than any dual channel DDR5 memory kit.
- tryauuum 11mo ago... shouldn't the logic be opposite? "Bad that SLI went out of fashion, there's no way for two GPUs to communicate fast over pcie, and SLI would allow such fast bridge"
- wtallis 11mo agoWhether or not SLI remained viable for gaming, Broadcom was going to jack up the prices on PCIe switches to the enterprise-only range. That's the real reason why consumer motherboards don't have more GPU slots. Mainstream consumer CPU sockets never had a wealth of PCIe lanes, there was just a brief span of years where PCIe switches were cheap so high-end consumer boards could offer several x8 or x16 slots (sharing bandwidth in ways that make diagrams like these important). In previous decades, non-mainstream CPU sockets were also more accessible to consumer budgets; first-gen Threadripper started at only 8 cores, so it was possible to pay extra for more memory channels and IO lanes without also buying an excess of CPU cores. But that had little to do with the popularity or viability of multi-GPU consumer systems.
- tripdout 11mo agoVery cool. Seeing how almost everything from WiFi, to NVME SSDs, (to apparently USB ports sometimes?) are connected to it, is PCIe the only high-speed interconnect we have for peripherals to communicate with modern CPUs?
- baby_souffle 11mo ago> PCIe the only high-speed interconnect we have for peripherals to communicate with modern CPUs? In a pedantic/technical sense, no. Practically speaking though, yes.
- stinkbeetle 11mo agoThe high speed signals that come out of mainstream CPU chips are generally DDR, SMP, and PCIe. Outside of a very few exotic things that use QPI or HT to connect, or exotic storage might use DDR, yes high speed off-chip peripherals use PCIe. NVLink is another one you might have heard of, although it might also fall in the exotic category. I think some systems take AXI off-chip too. So there's various other weird and wonderful things. But none you're likely to have in your PC I think. On-chip is another story, you can connect USB or NVMe or GPU "peripherals" using an on-chip interconnect type. But I guess you are asking about off-chip.
- crote 11mo agoUSB4 needs PCIe because its Thunderbolt part has PCIe tunneling.
- max002 11mo agoSo cool xD i think you could take it to tool with premoum features for people who are learning :)