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. The card needs at the most PCIE Gen 3 X2 == PCIE Gen 4 X1 in terms of bandwidth.
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: https://github.com/magic-blue-smoke/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.
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.
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.
Edit: Gen 3 x1 runs at almost a full GB/s, so a 2.5Gb/s card (notice the change in size of the “B”) should have more than enough bandwidth on Gen 3 x1, even at 2.5Gb/s full duplex.
A word of caution for anyone cutting out the slot: make sure there aren’t other obstructions, 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.
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.
The slot is open. I’m just wondering whether the card will work properly in that slot since all the pins won’t be attached. PCIe Gen 3 X1 bandwidth is more than enough for it
They all have to work (at least to an extent) using only x1. It’s part of the PCIe spec.
Missing pins are actually extremely common. If your board has a slot that’s x16 (electrically x8), which is very common for a second video card, take a closer look. Half the pins in the slot aren’t connected. It has the full slot to make you feel better about it, and it provides some mounting stability, but it’s electrically the same as an x8 that’s open.
