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
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.
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
Am I correct in understanding that the card will run at PCIe gen 3 X1 if I do this?
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.
What can I do if the card is PCIe gen 2 x8?
If you put a Gen 2 x8 card in a Gen 4 x1 slot, you will get a Gen 2 x1 link.
Alright thanks
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.
The ones on Amazon are intended to run GPUs for crypto farms, but they’re all brands you’ve never heard of with dubious claims and they’ve all got at least one review where either the device was defective or something was installed incorrectly and it caused damages.
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.
Oh. I thought they were using USB. Thanks
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.
I thought they were using the USB protocol. Thanks
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.
Technically the slot is PCIe Gen 4 x1, but I understand. TBH PCIe gen 3 X1 is fine too, that’s more than 6 port Gigabit cards can saturate anyway.
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.
Pcie 2.0x1 would have a theoretical max of 4gbit/s so it would probably only handle 3.5 gigabit of connections simultaneously.
