GPU and SLI advice

[davekw]

Hi everyone,

So after Grant's amazing work on my Iron Man model I decided I'd give the whole Octane/GPU rendering scene a go. My current card is a Quadro 4000 which simply isn't cutting it as any dense meshes like the Iron Man model makes my viewport and UI grind to a halt resulting in having to pause Octane, make shader changes, then unpause Octane, so I'm after a fairly decent card but nothing crazy like the Titans.

The two cards I've been looking at are the GTX 590 (on ebay for £140) and the GTX 780Ti (on ebay for £260) based on the OctaneBench results as they have pretty high scores for single cards but are both under £300.

So the questions are:

- Although the scores are very similar does one card have advantages over the other apart from the 590 being cheaper?
- Could I use SLI to link them to my Quadro 4000?
- Would it be better if the Quadro is used purely for 3ds Max viewport perfomance and the GTX purely for Octane rendering?

If it helps, my motherboard is a Gigabyte X58A_UD3R.

Thanks

[mib2berlin]

Hi, problem with dual GPU cards like GTX 590 is, they share its memory so if the card has 3 GB you can use only 1.5 GB for Octane.
GTX 500 is also old and may not a good buy long term, dunno if they even supported in Octane 3.0.
GTX 780Ti is a good card, if you can get a 3 GB card for this prize buy it.
You can get a GTX 970 for 320€ it is slower but a 4 GB card.
Look at the benchmark results:

http://render.otoy.com/octanebench/resu ... ingleGPU=1

Octane does not use SLI at all, you can switch cards on/off in preferences.
Btw. you can set render priority to low to get better viewport performance but slightly slower render performance.

http://render.otoy.com/universe.php#51T ... 20Settings

You can use Q4000 for display during setup and render on GTX and switch on Q4000 for final render.

Cheers, mib

[davekw]

Thanks for the info about the 590, I didn't know it could only use half the RAM. The 970 was my initial choice, but when I saw the 780 for that price I thought it was a no brainer. I guess it's hard to tell what the extra 21 points for the 780 would translate to.

[davekw]

So if the 590 is basically 2 cards stuck together and Octane can only use half of the total RAM, does the same apply to using 2 or more seperate cards? In that case would the total available RAM go off the card with the least memory?

[decade]

Yes, you're always limited to the lowest RAM of however many cards you're using, whether they're in a dual card or separate. But with dual cards, they always advertise it with the memory added together, annoying, I know.
People who have mis-matched cards sometimes have to use both cards on scenes with less RAM requirement and just the higher one on more RAM hungry scenes.
So the best card to choose is a balance of benchmark speed & RAM. The 780Ti Is fast if you think 3GB RAM will be enough for you. There were also 6GB 780s - They're slower than the 780Ti but lots of RAM. They're hard to find now though.

[smicha]

590 gives 1.5gb as said. It is also very power hungry and dissipates lots of heat. 780ti is a great card. If you need even better card 980ti with 6gb seems to be perfect. You can OC to get even 150 score in octane. And try to put same cards into your computer if possible.