Can I use a pci-e x16 slot for multple cards?

I have a mini itx pc with only one pci-e x16 slot. There is another old style pci slot.

I don't care that much about graphics bandwidth and I'd like to add USB 3.0 support. It's a waste to be using 16 lanes of pci bandwidth for a graphics card I hardly use, and I've found some convenient front panel usb 3.0 cards that only need a 1x pci slot.

I've seen products that allow people to split the pci slots into their seperate channels. They appear to be purely mechanical devices.

I'd like some advice regarding how to get my single x16 slot to support a small graphics card plus a 1x or maybe 4x usb 3.0 card. Some front panel usb 3.0 cards take up very little space at the actual pci-e slot as the cards main board is in the front panel unit.

What would be perfect would be a low profile graphics card that had a pci riser onboard but I doubt this exists and would probably be over priced if it did.

A graphics card that didn't take up the whole x16 slot might be acceptable if it's possible to use the last channel at the same time for a 1x riser or something, don't know if that's allowed.

I will consider acts of physical force on the hardware if deemed necessary to "persuade" it to comply. For example I've seem example of people putting x16 graphics cards into x1 slots just by opening the back of the slot and they still worked.

barrymac

Posted 2012-02-24T12:07:30.747

Reputation: 665

2PCI-e is intentionally designed such that you can fit one card in one slot, even if the number of lanes doesn't match. But you can't fit two cards in. That's because every card and slot has one set of control signals besides the lanes (at the very edge near the slotplate). Therefore, for two cards you need two slots. – MSalters – 2012-02-24T13:29:21.457

Short answer: You don’t. Long answer: see MSalters’ comment above. – kinokijuf – 2012-02-24T16:12:48.780

Answers

What you want is a riser card like this. The problem is that almost all standard cases won't accept the the add in cards, especially if they have external interfaces, unless they were designed with them in mind. Such cases are typically 2U rack mountable. Also, with this particular card, there may be other clearance issues since the cards point back toward the CPU.

MBraedley

Posted 2012-02-24T12:07:30.747

Reputation: 2 712

2You could grab a PCI-e extension cable, and put the riser card side-by-side with the motherboard. – MSalters – 2012-02-24T16:10:00.070

@MSalters: That would be an option that I didn't think of. You might get lucky and be able to mount it to the case, but that would probably assume a full (or at least mini or micro) ATX case. Since it's a mini-ITX motherboard, I'd have my doubts on the case being anything else. – MBraedley – 2012-02-24T17:16:25.223

Yes that's the kind of thing I was thinking about alright. There's also this impressive looking device, but I can be sure that's more than a new board. Problem with getting a new board though is that if I mange to find one that fits, and supports most of the hardware I'll lose my beautiful PCI based professional sound card. :-/

– barrymac – 2012-02-24T18:30:02.657

this http://www.bhphotovideo.com/c/product/547755-REG/Dulce_Systems_963_0700_0_PRO_EX_PCI_Express.html does what you specified, just in a large scale.

In the end you may find it cheaper to buy a convenient new motherboard?

user118305

Posted 2012-02-24T12:07:30.747

Reputation:

Similar to Alexander's solution mentioned before, you could use a "Magma ExpressBox". And this one is 30% cheaper, at only $2K.

[edit] I found a cheaper solution; a "Delock 61950 PCIe Docking Station" for about $800.

Seriously, a new MB would be the cheaper solution.

MSalters

Posted 2012-02-24T12:07:30.747

Reputation: 7 587

In theory: Yes.

You can plug in one card in it. That card can then forwards it data to multiple other PCI-e slots. There are some larger commercial solutions (e.g. the one linked to by Alexander Truemper), but the most common example is might be the NF200 chip. This did more or less the same and came build-in on some motherboards.

In practice it might be cheaper to buy a new motherboard with more PCI-e slots.

Hennes

Posted 2012-02-24T12:07:30.747

Reputation: 60 739