Cubix xpander

[Rhodesy]

Really a question for EricNV but somebody else might also be in the know about this...... Are there any plans to have a 3 x double slot X-pander? So you could have 3 GTX 480s in at once? I would think most folks are using double slot cards over the single so your really limited to two slots at the moment. For me the idea of a separate GPU box makes perfect sense but the restriction to two cards seems slightly mean when you've got the opportunity to go beyond standard mobo restrictions. I would rather have an option of a 3 x double slot unit that was say $200 more than be limited to just two which can be used in a bog standard PC costing probably less than the current xpander system. So I was wondering why stop at two? Also will the system work with any GPU renderer? not that you would ever want to use it with anything else than Octane Obviously the above is not talking about the pro rackmount system just a bigger expander!

Cheers

[havensole]

I've talked to EricNV about this a long time ago. I think that the issue might be how many times you can split the pcie bus. I think he said that using the xpander pro 2, or the rackmount version I can't remember, uses 2 of the host pcie slots. I agree it is a great idea, but 4x double slots as opposed to 3x. Why settle with 3x?
As far as putting other stuff in it, or using it for other purposes I can attest to that. I've used it for gaming here and there, where it performs beautifully. I've also thrown some pcie firewire and HD video capture cards in the xpander which have all worked great. Basically just look as the xpander box as an external pcie slot/splitter. It looks the same to the motherboard/system.

[Rhodesy]

yes 4 would be even better! I suppose then if they could do it with 2 data cables then that seems like a straight forward solution, I guess it just comes down to PSU size and price benefits. I imagine you can have 2 boxes running at the same time now through a single host PC but it will cost you. My thoughts were if you could upgrade the PSU to say a 900/1000w and add another slot then that might make it more appealing on a cost front if it was cheaper than just buying two boxes. But if there are technical issues getting the data down the cable then fair enough.

[havensole]

You raise a good, and very important point. Getting the data up and down the cable is a seriously difficult and complex thing. There is a slight slowdown in rendering when using an Xpander box because of this (very slight). The PSU would need to jump up to roughly 900+ watts as a single gtx480 uses something like 230ish watts at peak. I am sure if the interest in the Xpander boxes continues to grow and grow that we will see more interesting units coming from Cubix. Obviously they wouldn't throw money into an idea if they don't think there is enough interest to support the manufacturing of a new unit. So keep buying them up guys!

[EricNV]

Don't hold me to this, but we may implement a 3-4 GPU rackmount product (possibly deskside also) for the PCIe x16 version at some point later this summer. We'll have x16 ready to ship in the next 2-3 weeks for current configurations, and whether or not we do a 3-4 GPU configuration per Xpander will depend upon the price point increase of going from x8 to x16 bandwidth. The number of Xpander modules per 5U chassis may stay at 4, meaning a possible configuration of 12-16 doublewide GPU cards per 5U vertical rackspace. (I'd hate to be the guy who has to manage the HVAC for this thing!)

There is a logical reason to stay with 2 doublewide GPU cards per Xpander - fault tolerance. If one currently configured Xpander loses power (unlikely but possible), then only 1-2 graphics cards go down. You can populate your PC or Mac with as many GPU-Xpanders as you have open PCIe slots in the motherboard, so the hit from one unit going down is minimized.

If you have 3-4 graphics cards go down at once, more of your general rendering performance is affected. Again, this is unlikely to happen in either situation, but it is possible.

EricNV

[Rhodesy]

oooo Sounds promising there Eric - regarding the possible failure rate I think thats the choice/risk the consumer can make. I doubt its much different than if your main workstation goes down for any reason, but nice to know you have considered the user in minimising frustration anyway.

A 3 or 4 double slot x16 unit sounds ideal as a desktop solution and lets hope it can come in at a reasonable cost. I've seen EVGA do a 4xsli double slot mobo for about £400 but that in itself will require an extra large case and PSU to boot so your talking £700-800 as a starting point. I much prefer the separate render box idea though as it is a bit more flexible and hopefully the cooling solution and PSU has been speced to handle that sort of performance.

The debate then I guess moves on to buying the right GPUs at the right time! You dont want to be left with a bunch of cards with limited RAM and you're only as capable as your weakest card which is frustrating so it will mean wholesale upgrades across the system. Currently even the likes of the 480 is a bit short on the RAM stakes for more complex scenes and by the sounds of things youl be paying through the nose for the 3-6GB cards as they wont be gamer cards Good job Octane is a nice price!

[havensole]

I can see having a redundant PSU, or a separate psu for each group of 2 gpu's in the system. That should reduce the failure possibility some, though it would add some cost and reduce possible casing space. Cost wise I am not sure where it would land. Obviously more then the xpander for octane and the xpander pro 2. I can just see a huge 5 space rack box willed to the teeth with gpu's connecting to a little itx motherboard and a single pcie slot. That would be crazy, though I am not sure if possible.

The fermi based Quadro and Tesla cards should be out somewhat soon, but they will be far out of reach for most home users. Professionals should be able to get their hands on the Quadros at least. I am curious if the day will ever come with expandable ram for gpu's. That will be a good day.