Adding new card to maximize iray...using 4gb 770 now: what card would you get?
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I'm looking at a 980, 780ti, and a 980ti. If you have any other suggestions, i would like to hear it. I'm looking for cost effective...the 770 is going to continue duties driving the monitor, and the new card hopefully will significantly increase the performance. I am willing to build an external box, but that seems like a lot of hassle compared to selling the 770 and getting a titan z. I'd love to hear real world feedback.
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I have three cards in my workstation: An older 460ti to run the displays, a 780ti (3gb) and a 980 (4gb). They are all ASUS cards. The 780ti is the fastest card, but the etra gb of memory in the 980 is very useful, it also runs cooler. I am planning to replace the 780ti with a 980ti in the nbear future. Make sure your power supply can handle the extra card a load. The 780ti is more power hungry than the 980.
Ciao
TD
So does Iray only use the memory from the highest gb card? I'm a little unclear on this, as it seems you need to have matching gb amounts in order for the cards to be utilized. These are newbie questions, I know, but I'm trying to make a purchase that doesn't hobble me in some unforseen way. The titan z, while expensive, may actually be a bargain since it consumes a (relatively) lower amount of wattage (considering the number of cuda cores). Plus 12gb...that's sick. My PSU is 1000w now...I'm hoping it will be enough.
Iray will use the GPU memory in both cards, but it can only use up to the amount available in the card with the least free memory. In my case the 780ti is the limiting card. If I want to use all 4gb in the 980, I have to disable the 780ti.
The 1000W supply should be fine. I am using a 1050W PSU.
Ciao
TD
Oh, and make sure to carefully look at the Titan cards. The Titan Z is a dual GPU card that actually has 6GB per GPU, so your limit would still be 6Gb. The newer Titan X is a single GPU card and has a full 12 Gb available to render, That's what I would get if I would want to spend that amnounrt of money (which I am considering but I might stick with the 980ti).
TD
Not quite. Iray will load the scene to all selected cards - if you have, for example, a 2GB, 3GB, and 4GB card and all are selected a 2 GB or less scene will be rendered by all 3 cards. If, in the process of loading the scene, it blows past 2 GB the 2 GB card will drop out and the 3 and 4 GB cards will be used. If the scene exceeds 3 GB then only the 4 GB card will participate.
And double-check your power supply; I had a Dell T7400 with a 1000 watt psu - but it had five seperate 12 volt feeds at 18 amps; most Nvidia cards want 20 amps on the 12 volt feed.
So it is a trade off -- pick a 12gb card with 3000 cores, or a dual 6gb card with 5000 cores...
Yes, but the Titan X is a newer card. It uses Maxwell architeture vs. the Ttan Z which is a Kepler. Even though the Z has more cores, the X is faster: http://www.videocardbenchmark.net/high_end_gpus.html
Within one type of GPU architeture the number of cores and the speed are roughly linear, but between different GPU architetures that does not hold true.
Edit to add: The 980ti is a great compropmise, as fast as the Titan X and with respectable 6Gb of ram. A great price to performance ratio in my opinion.
TD
I'm sold! 980ti it is!
As mentioned, the 980ti is best for large scenes because of the 6GB memory limit. However, if you were satisfied with 4GB and have space in your case for 2 cards, the best "CUDA per dollar" value is in a pair of 970s, believe it or not. A single 980 has 2048 CUDA cores and runs about $500, which is about 4 CUDAs per buck. A 970 has 1664 CUDA cores and runs about $300, which, if you buy two, amounts to 3328 CUDAs for $600 or 5-and-a-half CUDAs per buck. The 980ti has the memory advantage, which really makes it apples-to-oranges, but with 2816 CUDAs and running around $680, makes it about 4.1 CUDAs per buck.
Good call. You're absolutely right, it isn't just about cores...
Keep in mind that video game benchmarks don't translate directly to iRay performance. If you're primarily getting a video card to accelerate iRay and don't care as much for games, then things are a little more complicated:
http://www.migenius.com/products/nvidia-iray/iray-benchmarks
As you can see the 780ti beats out the 980 there where the positions are reversed on the video game benchmarks. You might have trouble finding it anymore, but EVGA made a 6GB 780 card as well, which further muddies the waters :) The important thing to consider is that while objectively, the 980ti and Titan X are probably the absolute fastest cards for iRay rendering, the cost is rather high and you might be better off getting two lesser cards and saving a bit of money while getting better performance. Or even decide that you don't need that absolute fastest card and get a cheaper one that's 70-80% the speed of the faster one.
My wife just got the GTX 980Ti with 6GB and it flies through IRay.
Good points. Well worth taking into account. In my experience with IRAY and Octane, the difference between a 780ti and 980 (non-ti) is minimal. Those are the two render cards I have in my system right now. Here is the statistics of a recent render:
Total Rendering Time: 5 minutes 14.20 seconds
Iray INFO - module:category(IRAY:RENDER): 1.0 IRAY rend info : Device statistics:
Iray INFO - module:category(IRAY:RENDER): 1.0 IRAY rend info : CUDA device 1 (GeForce GTX 780 Ti): 945 iterations, 24.609s init, 285.610s render
Iray INFO - module:category(IRAY:RENDER): 1.0 IRAY rend info : CUDA device 0 (GeForce GTX 980): 937 iterations, 24.357s init, 285.856s render
As you can see the 780ti chomped through more iterations in the same time than the 980, but the difference is minimal (the 780ti is less than 1% faster). That's despite the signifcant difference in number of cores. If you are lucky and you can find one or two of the rare 780ti 6Gb cards, those would be a great choice. However, I have been unable to get my hands on those...
Ciao
TD
Yeah, I managed to get a 780 6GB refurb that probably sold out fairly quickly a short while back. Only EVGA made them, so there weren't a lot of them made in the first place. They're 780's and not 780ti's as well, so they're a little slower, but I paid right around what a 970 costs, so it was a pretty good deal for me. I think you can probably get some deals on older telsa or quadro cards, but those have other drawbacks as well (I've heard you can't run them in the same system as consumer cards for one).