Submitted 1 week ago by marauding_gibberish142@lemmy.dbzer0.com to selfhosted@lemmy.world
I’m looking at quad port 2.5Gbe Intel PCIe cards. These cards seem to be mostly x4 physically (usually PCIe gen 3) whilst I have a PCIe Gen4 X1 slot, which is more the theoretical bandwidth that the card can support.
How do I fit the card into a PCIe x1 slot? Won’t it lose performance if all the pins are not connected to the physical PCIe connector? Is there a PCIe x1 riser that the community likes that is somewhat affordable?
Thanks
Yea you may lose performance or may not, depends how the chip works on the actual pcie card. (Even if the slot has more than enough bandwidth at x1)
You can easily do a performance test after plugging it in though. Typically even an x8 interface will work with just x1 pcie connectors just slower. Even if that x1 interface is several generations later and has more bandwidth than that x8 needs lol
some ramblings of why just having the physical slots doesn’t always mean ___ can be found on this completely unrelated repo: github.com/…/Dual-Edge-TPU-Adapter (might be in an issue thread too unfortunately but he has more info here on how bandwidth works at that level than any other sites)
If you don’t want to risk modifying the slot, try one of the cheap PCIe risers on amazon and send it back if it doesn’t work. You will need a case with a couple of extra slots under the motherboard in order to fit the riser in there though.
It will run slower, but that probably won’t be an issue unless you plan to max out all 4 ports simultaneously.
I did this but buying these on Amazon is scary. Try to find one that won’t burn your house down.
Yeah, I definitely wouldn’t recommend putting something power hungry like a GPU in one of these. A NIC will be fine though.
Even maxing out the ports won’t be a problem. Even 6 gigabit ports don’t saturate a PCIe Gen 3 X1 slot in terms of bandwidth. But will the card work at all if all the physical pins are not connected electrically to the slot?
I cannot see any decent PCIE X1 to X16 risers on amazon. Everything is USB based which I don’t want
They are not USB based, they just happen to use a USB 3 cable to carry the PCIe signals.
USB the protocol, or just uses a USB cable? If it’s not using the protocol, the cables are a cheap way of getting cables of a certain spec.
Hand saw?
I don’t want to cut the card
Cut the slot? Or desolder it and replace it with one with an open back.
I don’t think you do.
A x1 will fit in a x4 but not the other way around.
How would I do it then? The card doesn’t exactly need PCIE gen 3 X4, at the most it needs PCIE Gen 3 X2 == PCIE Gen 4 X1 in terms of bandwidth.
In terms of physical connections you’ve said that the card needs the x4. Not sure what there is to say further.
Can’t get a 30 cm ruler into a 15 cm pencil case.
Maybe I’ve totally misunderstood your post.
Pretty sure if you put a PCIe 3.0 card in a 4.0 slot the slot will drop to 3.0, and 1 PCIe 3.0 lane probably isn’t going to work great with a card meant for 4 of them.
The card only needs PCIE Gen 3 X2 == PCIE Gen 4 X1 in terms of bandwidth. I was hoping to fit it into the slot since it meets the bandwidth requirements
An x1 slot is an x1 slot, the PCIe version will downgrade but there will still only be one lane because that’s all the slot physically has connections for. It will effectively be a PCIe 3.0 x1 slot.
If your card has an x4 pinout, then it probably needs the additional bandwidth. Plugging it into an x1 slot (if it was possible) would slow down the network traffic. Get a better motherboard with an x4 slot on it so you can use the hardware you want. or find something else that will fit your computer.
Honestly even the 1Gb quad port card I have requires an x4 slot, although I saw some dual-port 2.5Gb x1 cards on ebay. Maybe you could just use two of those?
It doesn’t need that kind of bandwidth. 6 gigabit ports cannot saturate pcie gen 3 x1 in terms of bandwidth anyway.
What do I do if the card is PCIe gen 2 x8 though?
Potentially the same thing, assuming PCIe 2 x1 provides enough bandwidth.
BombOmOm@lemmy.world 1 week ago
File a small slit in the end of the slot so the card fits into it, but runs past the back. The card will run at Gen 3 x1 speed, but otherwise work properly.
Many motherboards even come with the end of the PCIe slots open for this exact purpose.
litchralee@sh.itjust.works 1 week ago
A word of caution for anyone cutting out the slot: make sure there aren’t other instructions, like capacitors, ICs, and NVMe drives in the way of where the PCIe card will be.
The manufacturers that have the slot pre-cut will have already reserved the space, but even then, it’s on you to check that it’s suitable for a x16 if they only reserved space for a x8 card.
marauding_gibberish142@lemmy.dbzer0.com 1 week ago
I’ll likely go for a 4 or 6 gigabit port card, so PCIe gen 3 x1 is not a problem. Am I correct in understanding that the card will run at PCIe gen 3 X1 if I do this?
What can I do if the card is PCIe gen 2 x8? These cards from Silicom are really cheap on ebay
BombOmOm@lemmy.world 1 week ago
Correct. The situation you described in the original post would result in Gen 3 x1 speeds.
The interface will always default to the fastest standard that both sides can support. If one is gen 2 and the other is gen 4, gen 2 is the highest that can be supported. If one side is x8 and the other is x4, x4 is the highest that can be supported. In this specific case, if you put a Gen 2 x8 in a Gen 4 x1 slot, you will get a Gen 2 x1 link.