Upgraded from GTX-560 Ti to GTX-780, but Render Speeds are the Same?

Anyone know why I wouldn’t get a dramatic speed improvement when upgrading from a GTX-560 Ti to a GTX-780? Both are MSI cards (the 560 is a Twin Frozr, but 780 is not).

My motherboard is PCIe 2.0 and the 780 can use up to PCIe 3.0, but that shouldn’t make that much difference, should it?

I did a clean reinstall of the drivers and it actually got a bit slower, when from ~27 sec. to ~31. That makes even less sense to me.

PassMark ratings:
560 Ti - 3546
780 - 8035

Anyone got any suggestions? Is the plain-jane 780 just not that much faster than a 560 Ti?

I believe I’ve heard before that the ideal tile settings for your Cycles image may vary from card to card. It’s also possible that Cycles will also need to take a fuller advantage of new CUDA functionality before any serious speedups are seen (which may or may not require the dropping of support for cards like the 5xx series).

I’m just going about based on information that I’ve read before since I don’t do GPU rendering, but one needs to note that the rapid changes in architecture may require more extensive code changes to be fully taken advantage of (unlike the CPU).

Perhaps I’ve stumbled onto the answer.

I’d assumed that BI used the GPU and the tests I ran were in BI. But I’ve been doing some reading and since 2.67, all GPU support has been dropped from BI and it wasn’t CUDA GPU support anyway; that’s only ever been for Cycles.

I just assumed that if I had CUDA set in Preferences > System it was for both renderers.

(sigh)

I guess I’m going to have to bite the bullet and finally learn Cycles.

You can have more then one gpu in your machine at a time for cycles.

Is this actual GPU render time or does this include the BVH creation / compositing time as well? it will be more noticable on more complex scenes the speed difference.

Also what size are your tiles?

Thanks for the replies, guys. I was under the misapprehension that Blender Internal used the GPU. I’m sure it did at one point, but that’s no longer true.

@joseph raccoon: Yup. I just put my old GTX-560 Ti back in as a second card and got a 42% increase in speed.

@doublebishop: It’s the time that shows up in titlebar of the render window, so it includes everything, I assume.

But, I’ve now done some tests with Cycles (now that I know it’s the only renderer that uses the GPU) and got some pretty impressive render times:

System:
CPU: i7 2600k
GPU: MSI GTX-780 (no overclocking)
OS: Windows 7 x64
Blender version: 2.72b

With no changes to settings:
CPU: 2:18.05
GPU: 59.59

Optimized according to Andrew Price’s article:
CPU: 1:30.91
GPU: 22.66

And with both the GTX-780 and the GTX-560 Ti:
GPU: 17.64