possible to "split" a PCIe slot?

[Ghiddy]

Would it be possible to "split" a PCIe slot so you could put more than one video card on it?

I have some motherboards with two PCIe slots and I want to put a third ATI card for folding. I found things online like riser cards that seem to take one 16x lane and split them into 2 8x lanes, or 4 4x lanes, etc.

My thinking was if I could find one that was simply a splitter, would I be able to simply plug in two GPU's into one of the motherboard's slots? Would that work? Can the motherboard actually recognized all 3 cards if I did this?

I would basically take this out of the case so having two dual-slot cards side by side would not be an issue here.

 

[Modelworks]

No . You need a bridge chip to add another slot and those come on the motherboard and not in an add on card.

 

[Mark R]

Yes. PCI lanes are not arranged in fixed 'blocks', and lanes can be split off among multiple devices (with some limits). You can get adaptors like this for server boards - e.g the server has an 8x PCI-E slot, and you need a riser card to fit in the case. You can choose a 1 slot 8x riser, or one that splits the slot into 2 4x slots.

One very important sticking point could be the motherboard BIOS which may not recognise the presence of 2 or more cards in a 'single' slot. To get around this, you can buy 'active' splitter risers, which have a PCI-E bridge chip on. E.g. there are off-the-shelf risers that split a 1x slot into 3 1x slots, or a 4x slot into 4 1x slots. The presence of the bridge chip may also improve mobo compatability - but the price of these type of splitter rises is so high, it might actually be cheaper to buy a higher-end motherboard.

 

[JSt0rm]

yes it is possible guys. Its just expensive.

http://www.magma.com/