Adding more GPUs (than your case can fit!)

Tue Jul 01, 2014 9:35 am

Hey everyone,
I currently have a PC with 2 Graphics cards (GTX Titans). The more I use octane, the more I want to speed it up even further, I'd ideally like to add 2 more graphics cards. I'm guessing this would mean doing one of two things: Either changing to a case with 4 PCI slots (and possibly upgrading power supply) - or getting some kind of external caddy. Do these kinds of caddy even exist? What cases are available that have that many PCI slots? Am I right in thinking this means changing motherboard too?

I'm just looking into this, but if I can find an easy enough option it could be great! Would really appreciate you guys' advice! Thanks!

Tue Jul 01, 2014 9:57 am

hi, Mo.

there's a lot of solutions out there:

PCIe expantion boxes from companies like, Netstor, Magma, Trenton Sytems, etc to name only few. Much more companies are specialising at expansion solutions as it seems that's a growing market at the moment.

if You take expander route keep in mind that box'es like those are not the cheapest on the market..For enclosure alone You'll probably need to put from 1.5-2k$

You can get even more crazy & try something like [url+http://www.trentonsystems.com/backplanes/bpg8032-pci-express-backplane]20 slot backplane [/url] & use PCIe cable and host card of board computer enabaling system to work as a server =)

however if You're looking for a bit more rational upgrade & don't look to get more than 4 cards in one rig, maybe changing a mobo, case & PSU would be the best deal =) You can get 4 dual slot GPU compatible mobos for more or less any procesor familly (in this case You don't need to waste money changing ram/cpu, etc.)

as for the case it depends on Your needs, taste & budget. FractalDesign has some awesome built cases with mind on silent operation, Corsair has some huge beasts that got some atention from boutique builders, again, don't forget Case Labs as they have huge base of options & are very popular among moders & those who need insane cooling loops..-probably that would be threee companies I'd start lookin' at.

..but drop a line if You need more ideas =)

P.S. what systems You're running at the moment? =)

Tue Jul 01, 2014 10:14 am

wow... Glimpse, thanks so much for your help! Loads to digest there, good to know there are options. I'll look into each further. I don't think I can really budget dropping $1.5 - $2k on a GPU caddy, so maybe the motherboard / case option would work best.

That 20 PCI Slot backplate is extreme! Sounds a little tricky to set up, and probably not the tidiest solution, but damn... 20 GPUs would be something else!

I currently have an Alienware aurora R4. There is a little room in the case, but if I'm changing motherboard, I guess it makes sense to get a little more room in the case. (plus I find the case really ugly, to be honest!) Any idea what kind of wattage PSU I'd need to run 4 x Titans?

Thanks again so much for the gerat help!

T

Tue Jul 01, 2014 10:36 am

MoGrafik wrote:
I currently have an Alienware aurora R4. There is a little room in the case, but if I'm changing motherboard, I guess it makes sense to get a little more room in the case. (plus I find the case really ugly, to be honest!) Any idea what kind of wattage PSU I'd need to run 4 x Titans?

hehe, yeah I personally like clean cases too (XL R2, 9000D, SM8, 904, etc)

To run 4X Titans You should be ok with good 1200W as each T needs around 250W (some claim less), & some juice for the system, depending what You're running.

as for Titans, If You don't use those for DP workload & just doing raytracing, better get 780 6GB - those retail around $600 isntead of 1000$ for the Titans.. So what You would save from two cards You could spend for good case, PSU & some fans =) You will not feel any differene anyway =)

cheers

Tue Jul 01, 2014 10:44 am

Just chiming in here. Is it do-able to have 4 cards running and not use water cooled?

I currently have 2 titans, but would love to up it to 4, or add 2 780s

Tue Jul 01, 2014 11:27 am

gordonrobb wrote:Just chiming in here. Is it do-able to have 4 cards running and not use water cooled?

I currently have 2 titans, but would love to up it to 4, or add 2 780s

no problem, just provide good amount of air into case so cards would have enough to sip =)
worst case scenario, You might get throttle downs with small expence in render speed too keep those cards cool, but T's are very efficient (compared to earlier dfermis =D Just get a good case.

Watercooling migh give You better temps, maybe allow to overclock a bit..but for full loop You'd probably have to spend ~1k$ - sometimes it's just not worth.. unless You really need silent rig =)

Tue Jul 01, 2014 1:21 pm

I concur that airflow is very important. In my Mac Pro I have two Titan Blacks stacked on top of each other and the side door off. When I checked the rendering temps in Windows (OSX doesn't collect temps from the cards sensors) I was surprised to see them running at ~80ºC with the factory boost completely throttled down.

Not much I can do with the Mac Pro (as far as adding internal fans or spacing the cards out) but I found this Koolance external water cooler yesterday that I'm considering getting. If it doesn't need Windows to work, it could sit right on top and the tubes could go through the one open PCI slot. Sounds crazy, but it just might work. If it could bring temps down to 50-60ºC, that would be awesome.

Tue Jul 01, 2014 1:49 pm

riggles wrote: Not much I can do with the Mac Pro (as far as adding internal fans or spacing the cards out) but I found this Koolance external water cooler yesterday that I'm considering getting. If it doesn't need Windows to work, it could sit right on top and the tubes could go through the one open PCI slot. Sounds crazy, but it just might work. If it could bring temps down to 50-60ºC, that would be awesome.

if I were You, I'd get a pump (D5vario), 360 (thick, low preasure optimised), 3x fans (something like Noctuas), pair of waterblocks, standing pad, some tube & fittings.. - not so fancy, but more effective =) think Your temps will easilly be bumped under 50C..

Drop a line (via PM), & I'll explain some more if You wish =)

Tue Jul 01, 2014 1:51 pm

What's the limit of the driver, OS, or Octane or PCIe design? How many GPUs can you have?

Tue Jul 01, 2014 4:07 pm

voon wrote:What's the limit of the driver, OS, or Octane or PCIe design? How many GPUs can you have?

I think Windows and OSX start to have difficulties after 8 GPUs are directly attached, but I'm not 100% sure if I'm remembering correctly. Octane network rendering is limited to 12 per license, but I'm not sure if that applies to directly attached GPUs. My guess is that you'd hit a driver/OS limitation first.