PCIe 32x

[RoXXer]

Can linus plz try out PCIe 32x slot and what cards it supports

[NelizMastr]

8 minutes ago, RoXXer said:

Can linus plz try out PCIe 32x slot and what cards it supports

There is no 32x. PCIe goes up to 16 lanes, thus 16x.  There's 32-bit PCI, but that's WAY slower than even PCIe 1x 1.0.

[KarathKasun]

PCIe 32x is part of the standard, but it is not used in the consumer space.  AFAIK it is only used as a node interconnect in some esoteric (datacenter only) cluster setups.

 

ebay and Amazon have listings for PCI 32x stuff, but its actually PCI 2.2 32 bit stuff from decades ago.

[GoldenLag]

why?

 

there isnt any real demand for it either from linus nor the majority of the market

2 minutes ago, NelizMastr said:

There is no 32x. PCIe goes up to 16 lanes, thus 16x.  There's 32-bit PCI, but that's WAY slower than even PCIe 1x 1.0.

its a thing, except there is no use for it on the market. 

 

 

dual GPUs on a single card do have a PLX chip splitting 16 lanes into 32. though these 32 lanes do not have more bandwitdh than the 16 "real" lanes

[jj9987]

1 minute ago, NelizMastr said:

There is no 32x. PCIe goes up to 16 lanes, thus 16x.  There's 32-bit PCI, but that's WAY slower than even PCIe 1x 1.0.

Actually there is PCI Express x32 slot physically possible and it is in the standard, however it is simply not used due to length (pretty much double from x16 slot) and there is no need for that many connections. There are barely any cards that can take full advantage of PCI Express 3.0 x16. Besides 4.0 is coming to market and 5.0 is already in draft.

 

On the other hand, there are only few CPUs that can handle that many lanes.

[RoXXer]

4 minutes ago, NelizMastr said:

There is no 32x. PCIe goes up to 16 lanes, thus 16x.  There's 32-bit PCI, but that's WAY slower than even PCIe 1x 1.0.

Well ther is PCIe 32x slots. read comments below

[RoXXer]

4 minutes ago, jj9987 said:

Actually there is PCI Express x32 slot physically possible and it is in the standard, however it is simply not used due to length (pretty much double from x16 slot) and there is no need for that many connections. There are barely any cards that can take full advantage of PCI Express 3.0 x16. Besides 4.0 is coming to market and 5.0 is already in draft.

 

On the other hand, there are only few CPUs that can handle that many lanes.

Tnx for the fast reply. i will dig deaper

[GoldenLag]

4 minutes ago, RoXXer said:

Well ther is PCIe 32x slots. read comments below

the issue is; there is no real use for the slot. 16x slots allready do a fine job

[KarathKasun]

5 minutes ago, RoXXer said:

Well ther is PCIe 32x slots. read comments below

PCIe 32x doesnt have a slot and its not used for cards.

[RoXXer]

11 minutes ago, GoldenLag said:

the issue is; there is no real use for the slot. 16x slots allready do a fine job

Thats narrow minded, ofcourse we want faster slots

[KarathKasun]

2 minutes ago, RoXXer said:

Thats narrow minded, ofcourse we want faster slots

Not really, they would make trace routing a nightmare and you would not want to pay >$1000 for a MB.

 

Faster slots come with PCIe revisions.

[TopHatProductions115]

There are motherboard+CPU combinations that sport over 32 PIC-e lanes, but there is no physical connector that currently allows you to use 32 lanes for any one device. The closest you will get is by maybe using a workstation motherboard that also supports mGPU (SLI) - then the cards would possibly have access to 16 lanes each, and the mGPU configuration could technically count as an x32 device. That is, if it actually was using all 32 lanes allocated to it.

• https://superuser.com/a/1216442/446730
• https://www.tweaktown.com/reviews/8571/amd-epyc-7401-consumer-tested/index.html

If we were to try this experiment, the easiest (and most expensive) way would be to buy an AMD EPYC (with a compatible motherboard) and try running a few Dx12/Vulkan (or DxVk for linux users) applications to test GPU scaling in a promising workload. Epyc will have more than enough PCI-e lanes to accommodate this. Since Epyc doesn't require a chipset to operate, there should be little to be concerned about in terms of which PCI-e lanes come from what source, since most (if not all) of them should be controlled by an on-CPU die controller (in opposed to going through an intermediary chipset off-die). That's one of the primary reasons for why I decided that Epyc was a good option for the hypothetical experiment. If there are other CPUs that can run without a chipset (or if the article is somehow incorrect in this statement), please chime in. With that, I have no further suggestions.

 

#EnterpriseOnlyApplication

[GoldenLag]

1 minute ago, RoXXer said:

Thats narrow minded, ofcourse we want faster slots

for what?

 

note how many lanes the xeon 8180 has (48 lanes). only the Epyc 7601 has enough lanes to somewhat use it.

 

we get faster slot with PCIe revisions. currently we are on 3.0, and 4.0 is coming next gen. 

 

a 16x slot is way more versatile and gives bandwidth to most devices they will use.

 

mention what a 32x slot can accomplish that a 2 16slots cant.  

[Origami Cactus]

8 minutes ago, RoXXer said:

Thats narrow minded, ofcourse we want faster slots

Nvidia titan V or a gtx 1080ti barely saturate pcie 3.0 8x bandwidth, so in consumer market there is absolutely no use for 32x slot.

With pcie 4.0 around the corner, the 3.0 32x slot is pointless anyways.

 

Also what cards support it? All pcie cards. The same way i can plug a pcie 4x device into a 16x slot, i could put a 16x card into a 32x slot, but why?

 

 

[KarathKasun]

http://sullinscorp.com/news/news-releases/sullins-connector-solutions-pci-express-card-edge-connectors-available-with-up-to-32-high-speed-serial-pci-express-lanes/

 

Excerpt from supplier...

 

Quote

Parts are offered with 36(x1), 64(x4), 98(x8), and 164(x16) contact positions in right angle, surface mount, and card extender versions. Dip solder straight styles are available in 36(x1), 64(x4), 98(x8), 164(x16), 230(x24), and 280(x32) contact positions. The 230(x24) and 280(x32) versions are used to support riser card applications.

/thread

[Thomas_nerd]

On 9/18/2018 at 11:52 AM, NelizMastr said:

There is no 32x.

there is 32x just it is only in the server space

[NelizMastr]

On 12/13/2019 at 7:06 PM, Thomas_nerd said:

there is 32x just it is only in the server space

Congratulations on necroing a topic from september 2018. And 32x for a single card doesn't exist, only for risers which was already said a year ago.

[FancyPants101]

Here is a dumb Idea. What about making it a double slot and allow two 16 x or smaller cards. Maybe give it a way to any combo of smaller cards. 32-1x, 16-2x, 8-4x, 2-16x.

 

Back in the dos days this was common on machines. They had massive slots that could be used for large ram bays or other sideways mounted pci slots. The boards used to not always have the adapter slots. But a big slot with a card that had the expansion slots on it. What if it was for a massive combo of m.2 and other slots. Or for narrow/tall cards directly on the pcie 32x(more than one at a time.). Thin format only. There are a lot of utility cards that do not need back IO. If they started making thin format that did not go past the end of the x1 or x2 value length and was tall it could be nice. This could be good for short boards. Or to get a ton of extra stuff on a board. Maybe 1x32 pcie with a board for extra components and then 1-2 16x slots. The 32 could carry smaller formats. Maybe with a way to change them out for adaptability, or the ability to put multiple cards into the 32xpcie directly.

 

It might need special keyed slots though. It would need a slot every 1x length to allow proper spacing and to hold the cards in the correct space. then just put a bunch or cards in with some sort of holding. The old cases used to have bracket mounts for this. But I'm sure something could be done in custom cases built for the format. You would want taller cases though. If you put the 32x pcie it would need to be below the other items. Then you would want it to be able to mount cards down below the edge of the mobo. So lots of space would be needed for downward facing card adaptors. Unless it's directly in the 32x facing towards the side of the case. Then you just need wider cases in case it hits the side of the wall. Either way. Good thin design and airflow potential.

 

It's not just for server space. It's just not commonly used anymore. It could be useful if done well. You could even combine adaptor boards and raw board input. some could be facing the side of the case while others get partial adapter boards and then side ways direct mounted.

 

Better yet. Two 32xpcie slots. One can be primarily for shorter adapter boards, or side mounted. The second at the bottom of the board for downfacing adaptor slots. Although a lot could be mixed. Imaging how much stuff you could fit in once pc. Especially as cpu's get much bigger. When normal desktops are 256+cores this may be very desireable. If we improved raids and other logic we could get much more powerful storage and other io. And complete adaptabitity. You just need length concerns and nothing else. You could have all the connections you want in any format.