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Wow, 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
Nice! 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.
So 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.

Warning: addicting site :)
I’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?

I 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.
That 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.
Bifurcation support is also almost never mentioned, even if the bios supports it.
Yup. 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.
Very 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.
I wish all manufacturers clearly gave info like this up front. AM4 boards would be nice.
How can I contribute the data for the boards I own which are not on the site?
Whoa. This is so cool and helpful. Too bad my board is Intel. Is there a way to contribute to this?
Can 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.

If you really need lots of pcie lanes, you are going to be moving up to the TRX50 (or used TRX40) and its ilk. Different price ranges from your typical enthusiast MB though.
Check out the following for AM5 motherboards. It helped me a lot when I was in the market. Seems to be well maintained still:

https://docs.google.com/spreadsheets/d/1NQHkDEcgDPm34Mns3C93...

I ended up getting ASRock X870E Taichi Lite. The main reason to get it was because it had 2 CPU x8 slots which are spaced perfectly for an Nvidia NVLink. And, they are Gen5 PCIe.

Probably 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?
It's the other way around. SLI falling out of fashion is why there are no consumer boards with multiple x16 slots. There's no longer any demand for it on the consumer side, so the CPU vendors only provide lots of PCIe lanes for expensive chips.

On the server side, seven x16 slot motherboards exist.

I would expect x8 at 5.0 speeds to be plenty for SLI. That's twice as fast as x16 slots were around the end of the SLI era.
Very 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?
USB4 needs PCIe because its Thunderbolt part has PCIe tunneling.
So cool xD i think you could take it to tool with premoum features for people who are learning :)