PCIe "Splitter" vs. Ext. GPU Enclosure vs. +1 PC for GPUs?

[cgmograph]

Newish user here who has been absolutely blown away by the performance of Octane. I started with a 780ti and shortly thereafter added a Titan Black to my system that I got for an absolute bargain and am looking to add additional cards.

My dilemma, which I have heard echoed in these forums but haven't really found an all encompassing answer to is this:

My current system is pretty much maxed out for space with the two GPUs I have installed right now. It's a 4U case with a Supermicro board and deca-core dual Xeon's and 128 GB RAM + a small library of drives so I am getting a bit uneasy about trying to figure out ways to fit more GPUs in given how hot it has the potential to run already. To my understanding that leaves me with the following options:

1. Buy a second PC with a mobo designed for tons of GPUs such as this guy ( http://www.pcworld.com/article/2064502/ ... ining.html ) which probably puts me out around $750 - 1000 before I start buying additional GPUs and adds an additional layer of maintenance for networking the machines together. From what I understand this also comes at the cost of bandwidth limitations for file transfer and what not.

2. Use some sort of external enclosure a la netstor or another manufacturer of external PCI-backplates. Based on some research it doesn't seem like there are any solutions out on the market under $1k give or take so it's hard to rationalize that purchase vs. option 1, unless the bandwidth considerations were really that substantial.

3. Use a PCI "splitter" such as this: http://amfeltec.com/products/flexible-x ... -splitter/ - at a cost of $200 certainly much more reasonable but what kind of performance loss should I potentially expect going to PCI 1x?

4. Roll the dice with a similar product made in China ( http://eshop.sintech.cn/pcie-express-4p ... p-899.html ) at less than half the cost. Found a few forum posts related to bitcoin mining where people had used said splitters with success but couldn't find anyone here who could vouch for them.

I am all about the DIY approach if possible and can deal with my cards living out in the open if need be so options 3 + 4 have a lot of appeal given their cost but I am struggling to understand what kind of performance hit I may take.

Thanks for your help y'all.

[BorisGoreta]

I would suggest building an open rig like this:

http://render.otoy.com/forum/viewtopic.php?f=9&t=43795

So I am for option 1.

I have Netstor too, but it is too expensive.

The open rig shown can accomodate 5-6 GPUs, Netstor only 4.

Works very well over network.

Cooling is good since cards are spaced out.

Connect using fast network.

I haven't tried PCI splitters.

[smicha]

I must look at the splitters - never seen them before.

[glimpse]

thanks for links! Interesting products to say the least =)

You've mentioned some options but there is another one: Change Your motherboard & add cards inside SuperMicro case.

LAN box is an option, though some users suggest to have at least 1GB network or even InfiniBand (later will raise the price noticeably), if You don't wan't to notice lag..(data transfer & uploading effect)..

1x will influence loading time & guess it's up to You if it's ok (for main rig might be an issue, but for render node that would be capped by network data transfer anyway) it should be ok - Boris got some numbers on that.

Keep in mind that:

8GPUs (8 single or 4x Dual) seems the max limit if running windows
(pluss there is 12GPU limit if You utilise network rendering).

[cgmograph]

All - thanks for the insight.

For the sake of science (and this community) I might go ahead and roll the dice on the most budget option possible and see how that compares vs. my existing setup. If all else fails I am sure I can sell the card on eBay and explore more expensive options, assuming I haven't blown up my machine first.

Will post back here whenever I have had the opportunity to give it a spin.

[cgmograph]

Updating this again - after doing lots of homework I went ahead and purchased this guy to start for a princely sum of $5.49.

http://www.amazon.com/gp/product/B00HH1 ... UTF8&psc=1

I decided to give this guy a test first to see what what kind of performance hits I may take. The USB 3.0 route is an interesting one and appeals vs. a lot of the flex/ribbon risers (which seem pretty shoddily constructed) and offers a bit more length to make it out of my case if need be.

I am hoping I have time to install it and give it a run before I have to take off for the holidays but either way will report back soonish!

[BorisGoreta]

I bought 4 of these, 2 from 1 supplier and 2 from the other and both from one of the suppliers didn't work at all but the other two work perfectly.

[Seekerfinder]

I bought 4 of these, 2 from 1 supplier and 2 from the other and both from one of the suppliers didn't work at all but the other two work perfectly.

Hi Boris,
Care to share which suppliers worked & which didn't?

Cheers,
Seeker

[BorisGoreta]

I've compared my purchase orders and looked at the risers in my rig and concluded that actually one from each suppliers didn't work. Here are the suppliers. The first one ships from UK meaing you will get it much faster then the second one which ships from China.

http://www.ebay.co.uk/itm/1X-to-16X-Pow ... OU:GB:1120

http://www.ebay.com/itm/PCI-E-1X-to-16X ... OU:US:1120

Not wanting to be unfair to any of above mentioned suppliers what I can say is this: get a bunch of those risers because they are really cheap and then you have room to switch and replace if some of them isn't working.

[Seekerfinder]

Thanks Boris.
Seeker