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 Post subject: Experiment in PCI-E x1 folding - with PPD numbers
PostPosted: Thu May 02, 2013 5:33 am 
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Recently, I made a renewed push to cut down on the number of machines I have running 24/7, to save on the ol' electric bill. For a while, this meant taking the GT 640 I picked up cheap(ish) out of folding, because the machine it was in really had no reason for being on all the time (aside from folding). But then I did some googling, and found out that some of the bitcoin folks were doing GPU computation work with all sorts of cards (even quite powerful ones) by using adapters to connect the PCI-E x16 physical connector to PCI-E x1 slots on motherboards that don't support SLI/CFX (or they're using 4+ GPUs in one system and all the x16 AND all the x1 slots have graphics cards hooked up to them - those pictures are nuts).

That got me thinking that my one remaining 24/7 folder already has a GTX 650 Ti in its lone PCI-E x16 slot, but it also has two PCI-E x1 slots :D

Last night, my PCI-E x16 to x1 adapter arrived in the mail, and after some crude mounting work involving a miter saw, some leftover molding, foil tape, zip ties, and a 1.25" drywall screw, the GT 640 was nestled snuggly next to its big brother GTX 650 Ti. (Regarding the sketchy mounting job - making due with what I've got...but trust me, pics would not be worth it except for the laughs)

The forum threads I read previously said there could be issues with drivers not recognizing the card unless you install it in the x16 slot first, needing to use drivers from Windows update instead of nvidia/amd's packages, and all sorts of possible pitfalls. But, booted right up, drivers work fine (same ones I was already using for the 650 Ti, I think it helped to already have another nvidia card in the machine)

Next up was to OC the 640 with EVGA PrecisionX to the same clocks it was at in its old home, get the folding slot configured (I'm using the v7 client), and wait to see some hopefully pleasant PPD numbers:

The little guy is currently chewing on a WU for Project 8070, 55% complete as I'm writing this post.

    TPF: 5 min 52 sec
    Estimated PPD: 9508


For reference, in the old box, this card was getting between 8k and 10k PPD (depending on the WU). So, it seems, for current WUs, and with a relatively weak GPU, PCI-E bandwidth is not really an issue for GPU folding. I can't really draw any more general conclusions from my one data point, but I'm a happy camper! Anyone else tried this or actively doing this already?

Additional hardware specs and info if anyone is curious:

    Motherboard is running the P45 chipset (LGA 775 board with a 45nm Core 2 Quad in it), so my GTX 650 Ti has a full 16 lanes of PCI-E 2.0 available, but the GT 640 is only getting one lane of PCI-E version 1.1 bandwidth, because the x1 slot is fed from the ICH10R southbridge, which only supports PCI-E v 1.1

    Because the GT 640 does not have its own PCI-E power connector, I purchased a PCI-E x16 to x1 adapter cable with an injected Molex power connector, to make sure the GT 640 would not try to draw too much power from the motherboard itself. I was worried about this because what I've read seems to indicate that x1 connectors, by design, cannot supply enough power for a PCI-E (PEG) graphics card, even a relatively 'wimpy' one like the GT 640. If I'd been using a GPU which had a 6 or 8 pin PCI-E power connector, this probably would've been unnecessary, but this project was all about making use of what I already have, with minimal additional expense.


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 Post subject: Re: Experiment in PCI-E x1 folding - with PPD numbers
PostPosted: Thu May 02, 2013 8:00 am 
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very interesting! Great work. Way to use the hardware you have on hand :twisted:


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 Post subject: Re: Experiment in PCI-E x1 folding - with PPD numbers
PostPosted: Thu May 02, 2013 11:55 am 
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Gero1369 wrote:
very interesting! Great work. Way to use the hardware you have on hand :twisted:


Thanks! The wife (and our mutually agreed upon budget) wouldn't have it any other way :lol:


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 Post subject: Re: Experiment in PCI-E x1 folding - with PPD numbers
PostPosted: Sun May 26, 2013 8:54 am 
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Sorry but... someone's gotta ask-

I've gotta see the pics! -for the laugh at least.
Any way you can post them AliusBU?
C'mon, give us the goods bro!

There are pics on this forum of people routing the cool air-conditioned air coming out of their floor registers straight to their boxes using CARDBOARD and DUCT tape! Hehehe! Those were awesome pictures. So share 'em bro!

Thanks for the info on the adapter. Do you have a link where you got them at?

The minimal-#-of-boxes/maximum-output-per-box concept is on everyone's mind.


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 Post subject: Re: Experiment in PCI-E x1 folding - with PPD numbers
PostPosted: Thu May 30, 2013 5:26 am 
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ddforrester wrote:
Sorry but... someone's gotta ask-

I've gotta see the pics! -for the laugh at least.
Any way you can post them AliusBU?
C'mon, give us the goods bro!

There are pics on this forum of people routing the cool air-conditioned air coming out of their floor registers straight to their boxes using CARDBOARD and DUCT tape! Hehehe! Those were awesome pictures. So share 'em bro!

Thanks for the info on the adapter. Do you have a link where you got them at?

The minimal-#-of-boxes/maximum-output-per-box concept is on everyone's mind.


Aww man, I just swapped the GT 640 out last week. Building myself a new mini-itx box that supports full-height GPUs, so I swapped in my single-slot half-height GT 430 in its place. Since the 430 is a slimline card, I was able to screw it in normally - so no more zip ties, foil tape, piece of molding, drywall screw, etc. Funny thing is the GT 640 was probably in there more securely than the 430 is now, but it's such a tiny card I'm not very worried about a slight wiggle.

I was definitely not the first to come up with this idea. Credit for convincing me it would work goes to this thread over on overclock.net. That person was using a really low powered card which didn't use a PCI-E power connector. The GT 640 uses a bit more juice, and I was concerned the x1 slot (missing all the extra power lines that a x16 connector would have) wouldn't cut it, so I got the more expensive cable adapter which uses a molex connector so that the card draws power from that instead of the motherboard.

I got the adapter here. He appears to be doing a booming business among the bitcoin mining community. The tape he uses seems a bit suspect but the solder joint is solid and the adapter does what I need it to, and worked with two separate GPUs so far.

The ironic part is if I had been using a higher-end card that had its own 6-pin PCI-E power connector, I could have probably gotten away with using a cheaper adapter without the molex connector, but this project was all about making use of what I've already got in the house. I contemplated trying to use a dremel to cut off the back of the slot on the mobo itself, but there wasn't enough room for that and I was worried about the power issue anyway.

Awesome picture (not mine, but wish it was) here too


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