CrossFire/SLI Through a single PCI Express x16

Sorry in advance if this is in the wrong section

Thinking about upgrading my PC to a 4k able machine, i currently have an itx build for portability to and from Uni, i was wondering if it is possible to run 2 cards in crossfire or SLI through a single x16 PCI Express slot using a Riser/Splitter.
I know if it could work there would be a performance reduction but just wanted to check if it was a possibility before splashing out on a full upgrade.

Gigabyte Z87N-Wifi
i5 4670k @4.4GHz Water Cooled
RM650w Psu
16Gb Ram

Thanks In Advance

r9 295x2 is a dual gpu card more than powerful for 4K

It is possible using a dual GPU card. The AMD r9 295x2 or the powercolor r9 390 devil 13 ( it is a dual r9 390) the fury x2 is going to be released soon. These cards are the ones that I recommend

But running 2 separate cards off of 1 slot using a riser and splitter is not recommended. The performance loss and the amount of headaches that doing it that way is not worth it. You will be better served using dual GPU cards .

You would have to wait for a Dual GPU card like the Fury X2, however you might as well just get a nano, as a nano by itself can do 4k gaming alright so long as you aren't crazy enough to turn on AA

I feel like (and I'm not an electrical engineer so feel free to correct me) a single 16x slot can't run enough power for two cards at once, let alone have enough bandwidth to share between them.

It seems like it would be possible, but I've never seen a PCI-e splitter.

What you are asking about is a phenomenon known as PCIe bifurcation. The TL:DR is that yes, it is possible in theory and even workable in some cases, but these are rare and difficult.

Bandwidth-wise, one PCIe x16 slot is fine, and the physical adapters are easy enough to het hold of, but it's the firmware and software that make it difficult. It really depends on your motherboard and GPU. I would get on the Gigabyte forums and start poking around Hardforums,, and Tom's Hardware for specific threads about your board. We can speculate about it here, but chances are that Gigabyte can tell you right away whether bifurcation will work on your board. If it does, you'll probably need a special bios and a few other tricks, and from all reports, you'll be dealing with jankiness on a regular basis, as it's not really a use-case that any of the parties involved test for. Definitely not for the faint-at-heart. Of course, you could save up and upgrade to a larger motherboard with more slots. Good luck!

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