PCIe Expanders

[TransAmDan]

If you dont have enough PCIe ports in your PC for GFX cards you can plug in an expander. This with riser cards, use one port to generate 4 ports. Much like a USB hub.
Shown below a PCI port from the motherboard detected a PCI-E switch and on eah port of that switch detected the card plugged into it.

Can you plug an expander into a port from an expander and cards still be detectable? i wonder. and I will try this when another expander card arrived.
My motherboard has 3 PCie slots, one needs to be used for the GFX card so a display can be seen. So the other two can have expander cards in them. Giving me a total of 9 available ports. If I can plug an expander into an expander I can gain an extra 3 ports.

 

[Nelly]

My vote is you cannot plug an expander into an expander but I am ready to be proved wrong, how did it go?

 

[TransAmDan]

Not had a chance to try it yet. I have a PC I can try it in though, and very keen to see if this is possible.

I have two expander cards, and 3 risers. I also have two other cards, think they are just extra USB3 ports. So my plan would be to plug one expander into the motherboard, from that, plug in one riser. then an expander card into that. From that 2nd expander card I'll plug in 2 risers, and each of them having this USB expander card. I'll see how it looks on the PCIe listing like in the first post.

Would be interesting to see if it works. Of course I expect there will be bandwidth limits if you put too many on there. From the motherboard using PCIex1 its 250Mb/s. Each GFX card is using around 18MB/s of usage while mining. So in theory up to 13 GFX card per one PCIe slot on the motherboard before you would see bandwidth issues.

 

[TransAmDan]

Yes it works, you can expand and expander

My rig currenly had 8 cards. It has 3 mother board slots. i was aiming for a 12 card rig at one point. but due to the CPU I have there is no onboard GFX, so I cant expand all 3 slots. So limited to 9 cards unless the expanding the expander route works.

The expander cards I am using,

Its a China product, but cant find any of these made in another country.

I plug one of the PCIe expander direct into the motherboard. Then usb cable to the riser, in that riser I put in the other expander card.
In that expander card I attached 2 more risers.

In those 2 additional risers I put in 2 spare cards i have laying about, these are USB cards, if windows can see these then it could be safe to assume it would see a GFX card in those slots. i didn't have any spare GFX cards as they are all in the mining rig.

Using HWinfo64 you can see the PCI bus. In port #8 highlighted we can see the PCI Express x1 Bus #4, and see the ASMedia ASM1184 PCI-E Switch, this is the first expander card, In that we can seer the 2nd ASMeria ASM1184 switch, and in that we can see the two cards I have plugged in, the two cards I plugged in were just extra USB ports, and i tried them and they worked.

So it does appear that you can plug in an expandercard into and expander card, and windows does see the cards plugged in. So I'd call that a success.