Modify x16 riser cable to be x1 to x16?

[Miracek]

Has anyone tried modifying a Pci-e x16 riser cable to be x1 to x16? I've tried this for 2 of my cards, when installed, it wasn't very stable and on of the cards had it's load varying from 64% to 100% several times a second.  Took everything apart and put it back the way it was, 2 GPU's on 2 mother boards, just so I can keep mining as I was.  Upon close inspection I found that I nicked the last connector on the riser cable, it was passing continuity but barely.  I figured I should ask if this works before trying it again.

 

[swordfish6975]

not the link i remembered but some good info:

http://blog.zorinaq.com/?e=42

It is not very well known, but the PCIe specification electrically supports down-plugging a card in a smaller link connector, such as an x16 card in an x1 connector.
However PCIe mechanically prevents down-plugging by closing the end of the connector, for a reason that I do not understand.

Some motherboards require pins A1 and B17 to be shorted for an x16 card to work in an x1 connector.

[Miracek]

Thanks Swordfish

I had seen that link before attempting my mod, there was another link I had seen where someone actually modified their graphics card by removing the additional connectors and had it physically inserted into the x1 slot.  that's what gave me the confidence to at least try.  As for the shorting of pins to allow the Mobo to detect the cards, fortunately my board didn't need that mod, CGminer saw and was operating all 4 cards, it's just the performance was not great, and I think the card with the connector I nicked while remove the rest of it connector was going crazy on the GPU load before I shut it down.

[grue]

[...]it's just the performance was not great [...]

I get the same performance with x1 as x16, even mining scrypt. :/

[deslok]

bitcoin mining does not require the full 16x lane, most cards actually peak with a 8x lane even. if you're seeing poor performance after modifying a riser something went wrong with the modification(or perhaps the riser was no good in the first place) 5870 makes this old but this is a good read still
http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/25.html

[Miracek]

Yeah I agree, I definitely cut through a part of the last copper pin when modifying the x16 riser.  I'll probably mess around with it tonight and trying just put the 3 cards in one machine and see if that's stable.  If it is I'll try to modify another riser cable and then put all four cards on the same Mobo.  I just posted this up here to see if anyone else has done this and if there were any specific things I should look out for.  or some tips on the best way to cut down the x16 riser to x1.  I currently am using a dremel with a cutting wheel on it.

[deslok]

try an oscillating multitool it'll be easier to handle than the dremel(won't try and spin either up or down the card)
http://www.harborfreight.com/oscillating-multifunction-power-tool-68861-8493.html

[Miracek]

I know, unfortunately I loaned my Multi-tool to  buddy working on his house and he's on vacation this week, didn't think I was going to need it so I didn't ask him to return it. 

[ReCat]

not the link i remembered but some good info:

http://blog.zorinaq.com/?e=42

It is not very well known, but the PCIe specification electrically supports down-plugging a card in a smaller link connector, such as an x16 card in an x1 connector.
However PCIe mechanically prevents down-plugging by closing the end of the connector, for a reason that I do not understand.

Some motherboards require pins A1 and B17 to be shorted for an x16 card to work in an x1 connector.

Wait. So if I remove the end of a PCI-E 1x connector on the motherboard, so that a PCI-E 16x card will slide into the slot, it would just work?!

[deslok]

as long as you have clearance and don't damage your motherboard? usually, not everything works as intended but it's supposed to.

[Global BTC]

You could also use a 1x to 16x extender:


For some cards, you need a powered extender.

[ReCat]

as long as you have clearance and don't damage your motherboard? usually, not everything works as intended but it's supposed to.

Dang. I could do that with a dremel, just drill away the plastic at the end. Why don't they do that normally? Would be great for fitting two GPU's right into the case of most desktops that don't have a x16 slot.

[deslok]

as long as you have clearance and don't damage your motherboard? usually, not everything works as intended but it's supposed to.

Dang. I could do that with a dremel, just drill away the plastic at the end. Why don't they do that normally? Would be great for fitting two GPU's right into the case of most desktops that don't have a x16 slot.

Because it's not normal to stuff that many gpu's in a system and things like crossfire and SLI aren't supported that way. I've seen some boards with an open ended 8x slot designed for workstation use but that's about it.

[Miracek]

You could also use a 1x to 16x extender:

For some cards, you need a powered extender.

Unfortunately I don't have x1 to x16 adapters, but I do have a bunch of x16 riser cables, so I was trying to make my own x1 to x16 risers from those.

[sweeppicking]

I make it, x16 x16 didn't work on my computer so i cut it, now i'm using it like a x1 x16 riser and can make another x1 x1 but i need the top famale pcie conector.

[Miracek]

I make it, x16 x16 didn't work on my computer so i cut it, now i'm using it like a x1 x16 riser and can make another x1 x1 but i need the top famale pcie conector.

Thanks sweeppicking glad to hear it works.  I could not find a reason it wouldn't work but wanted to make sure it would.

[sweeppicking]

I make it, x16 x16 didn't work on my computer so i cut it, now i'm using it like a x1 x16 riser and can make another x1 x1 but i need the top famale pcie conector.

Thanks sweeppicking glad to hear it works.  I could not find a reason it wouldn't work but wanted to make sure it would.

Just need to cut the kables, and care with the male pcb cuting. x1 x16 is beter that x16 x16.

[Miracek]

Good point, I didn't think of that. In the process of cutting the male board that connects to the Mobo, i should also sever the cables running up to the card.  THis was if there are any shorts that I may have made by cutting the board they won't actually be connected to the GPU.

THANKS 

[zackclark70]

just cut the back of the motherbord slot

[Miracek]

don't think that would work on my board. 2 of the x1 slots are between 2 x16 slots, but at some point between the 2 x16 slots there is some thing on the board with what looks like an integrated passive heat sink, it would get in the way of the x16 riser cable.

EDIT

I will take a look though, I'm just going off of my memory right now.