Performance question

[filipe_sheepwolf]

Hi,
I've been using 2 GTX 465 to render with octane
Each one has 352 cuda cores, So, I had a total of 704 cuda Cores

I finally upgraged my graphics cards, I replaced the two gtx 465 by 2 gtx 770
Each 770 has 1536 cuda cores, so now I have a total 3072 cuda cores

Shouldn't my render speeds be 4x faster now? I've read that octane scales linearly with the number of cuda cores (and the example of a gtx 690 with 3072 cores would be twice as fast as a 680 with 1536 cores)

I saved my render times from some scenes, and now I tested them with the new graphics cards, but I'm only getting half the speed (instead of 4 times less speed, and yes, I set the cuda options to use both graphics cards, and Sli is disabled)

Another thing I've noticed, the 2 gtx 465, are rendering faster than a single gtx 770 (I mean, if two gtx 465 are 704 cores in total, how could they be faster than the gtx 770 that has 1536 cores?)

[kavorka]

there is more to it than that. I think that there is a clock speed on those cores and its different for each card.
Octane scales linearly with cards. So, 2 gtx 590s will give you double the speed of a single 590. and a 590 and 470 will give you the speed of each card combined with no loss.

[FrankPooleFloating]

I believe 1 Fermi core (400 and 500 series) equals 3 Kepler cores (600 and 700 series)...

So your 704 Fermi cores are like 2112 Kepler cores... This is why 580's beat 770's and 680's.. and not terribly far behind 780's...

You did not jump high enough bro, imho - had you asked before buying, folks would have suggested bumping up to 780's, for sure. You are definitely saving energy though.. that is kinda cool.

[filipe_sheepwolf]

Well, at least I know there's nothing wrong then.

Thank you for your answers, I wished that choosing a graphics card was as easy as the octane FAQ made it look (double the cuda cores = double the speed...)
At least now, my new system is badass enough to play games in ultra