Dual GTX970 cards?

cdpro_2831bbd990

Hi, I read what else I could find during a search.  I'm getting that when using two GTX cards for Iray that 1. SLI should not be enabled and 2.  If the scene cannot fit in one card's memory, then it will not be used during the render.

So, my question is this:  If I use two matched (same brand, same model, same memory) GTX970 cards, does that ensure that both cards will always be used during iray renders?

Since GTX970 cards are available for about half price right now, I thought this might be a good way of doubling CUDA cores and cutting render time.

Anyone have experience with this particular setup?  If so, is there any best method for optimizing?

My current system:

i7 4790K

GTX970 G1 Gigabyte 4gb

16gb DDR3 2400ghz

The single card is currently running 2 monitors in 1080.

Thanks for any input!

I'm trying to figure out where best to put my money.  GTX970 like mine can be had for around $189, currently.  So, how effective would a dual setup be compared to buying the newer 1070 as a single card upgrade?

mjc1016

If you have t cards with the same amount of memory (4 GB)...it doesn't matter if they are 'matched' or not, that's the limit...4 GB.  BUT...since one is running ayour monitors, it would probably drop out because it will have less available memory due to that fact.

What would be best...get the 1070 and keep the 970, for running the monitors and assisting when it can.   You'll have a lot more room to play, that way.

Richard Haseltine

Do bear in mind, however, that if one card is beig used to drive the display(s) and the other isn't then one may have less free memory than the other, and so may drop out sooner. This will also depend on the OS you use.

heinzerbrew_f94794efff

Ary you sure that Daz Iray supports 1070?

mjc1016

The beta does (4.9.3.128), the 'current' version 4.9.2.70 does not. 

cdpro_2831bbd990

Thanks for the replies!

So, it is possible to drive monitors with a 970, but use a faster card like a 1070 to do the Iray work?  I thought the 1070 would be dragged down by the 970's limitations.  I thought you couldn't use unmatched cards.  If I am using one card to just drive monitors, is a 970 even necessary?  I could put that in my other machine and use something cheaper to drive the monitors.

Answer me this...What is the best case scenario?  Will I get more out of a video card upgrade, or a cpu / memory upgrade?  I've considered going to a dual CPU system...but only if it will greatly speed up renders.

mjc1016

Unmatchecd cards don't work for SLI...

Yes, you could drop in anything, really to run the monitors.  Some even run onboard video for that.

If you hav sufficient video memory/small enough scenes to stay on the video card, so that you seldom/never use CPU mode, then upgrading the CPU won't really help with rendering.  Also, more RAM won't help with GPU rendering, either.  BUT, both will help with everything before you hit render....and if you do drop to CPU mode, yes, they will be beneficial there.

cdpro_2831bbd990

Thanks for the explanation.  From what you are saying, it sounds like a single, faster card with more memory is still a better performance increase than adding a second 970.  I had hoped to get double the cores and maybe that would translate to perhaps 180% performance over a single 970.  But what it sounds like would happen is that one of the cards would drop out if memory usage is more than 3.5gb.  If that's the case, then having a second card won't really help on big renders...which was the point of adding another card...speeding up those renders that take all night.

mjc1016

Right...the 970 will use the full 4 GB if it isn't running a monitor, too. But a 1070 with 8 GB pretty much beats a single 970 and  isnt too bad against two (I think someone posted that run in one of the long threads), but since ti has 8 GB it will 'last' longer...it'll keep going were one or both of the 970s have dropped out.   And in the case where upto half that 4 GB can be used/reserved by everything else (running the monitors), it doesn't take too much to drop down to a single card rendering.

nicstt

It would be worth considering a 10 series card.

Keep the 970 to drive the monitors; I use a 970 to drive 3 2560x1440 which it does without issues.

I use a 980ti for rendering and rarely add the 970 for the extra cores as one, it gets laggy, and two, it drops out quite often anyway, and it really increases noise and heat production.

So a 1070 would be pretty decent from the posts i've seen of its performance; 8GB is a good amount of RAM and you current system will cope reasonably well. I just think 10 series cards are over-priced.

cdpro_2831bbd990

Hmmm...considering all that has been said about how the cards can work together without SLI, this begs a big question:

How difficult would it be to put something like a 1070 in a box linked via Thunderbolt or USB 3, to a laptop in order to give it a big boost in GPU processing?  I assume you'd need the box to have a decent power supply to drive the card and cooling.  But otherwise, it sound like the main thing would be getting the PCIe card to read and write over a cable instead of being mounted on the motherboard.

Anyone try this?

If it works, it would really help people like me who bought a good laptop last year (MSI Apache 72 w/ GTX970m graphics) to boost mobile performance without buying a whole new laptop.  I really love the laptop.  But, it renders at about 2/3rds the speed of my desktop.  I'd love to be able to add some CUDA cores to it without breaking the bank.  I know that there were laptop versions of the 980ti that were the full deal, not the "m" designation.  So, I'm sure there must be some for the newer cards as well.  One of those smaller format cards with a notebook power supply attached via Thunderbolt might work.

Just some thoughts...

Artini

... but if you ever find a way to put a box with the 1070 linked via Thunderbold or USB 3, to a laptop

it will become to be just another desktop computer. And I doubt it can be easily done with the current technology.

But you can always dream about it and may be some day, such solution will become available.

GaryH

You could try hooking your laptop to a Razer Core External Graphics Dock via Thunderbolt 3.  While designed for the Razer Stealth laptop, others have got it working with different laptops.

It's a brilliant looking enclosure, but it costs as much as a GPU.  http://www.razerzone.com/store/razer-core

Here is a discussion that includs how hart breaker got his Razer Core working with an MSI GS40.  https://insider.razerzone.com/index.php?threads/razer-core-with-non-razer-laptop.14337/page-5