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I was comparing the other two systems with the Octane Benchmark Scene and a few other scenes.

My 'Toy' at home:
http://www.amazon.de/dp/B00F9PSB8E/ref= ... _M3T1_dp_1
(GTX780M)

(sorry for german, you get the specs)

and a workstation:

HP Z420, 8GB Ram, Xeon E-5-1620 @3.7GHz, 8 Cores
equipped with GTX 780M, 3GB

Both 64 Bit.

I expected a speed icnrease for Octane by factor 3-ish, because GTX760M = 768 cuda cores and GTX 780M ~ 2200 Cuda Cores. But the Workstation gives a speed increase roughly factor 4.5-6, for some scenes bit more, for some bit less. Does memory bandwidth etc. also contribute here.

The Benchmark scene gives ~1Ms/Sec as loaded for GTX760M, and ~5Ms/sec for GTX780. Pathtracing, alpha shadows on. Just opened the benchmark scene, switched to PT and press 'play button'

I am not annoyed that my expectations are surpassed, just confused.

Hi Vue2Octane,

Vue2Octane wrote: and a workstation:

HP Z420, 8GB Ram, Xeon E-5-1620 @3.7GHz, 8 Cores
equipped with GTX 780M, 3GB

Assuming you mean GTX780 (not M) for your workstation, that card has 2304 cores at a base clock speed of 863MHz. This is not the sum-total of a card's processing power but for the sake of argument, let's compare the 2 cards:

GTX760M: 768 cores x 657MHz clock speed = 504576 (it's just a factor for this purpose)
GTX780: 2304 cores x 863MHz (base) clock speed = 1988352

Theoretical increase: 3.94

Like I said, there are other factors and while I don't know them all, temperature control (including throttling) and drivers are two typical ones.

Best,
Seeker

Thank you for comparing the two cards.

On the Octane Website it says the render speed of Octane scales with Cuda Cores. I assume they mean two identical cards in the same rig.

Good to know that clock speed x cuda cores is overall unit.

Bandwidth, Temperature etc. might then add to this, you are right.

Vue2Octane wrote:On the Octane Website it says the render speed of Octane scales with Cuda Cores.

It's true of course but it's not a linear scaling. And, unfortunately, not everything is in the software developer's control. For instance, Octane (and some other apps) were way more efficient - cuda for cuda - in the Fermi architecture than the subsequent Kepler by Nvidia. So there was a 'negative scaling' between those two processor architectures. Thankfully, GPU computing has a very bright future and new, lower energy solutions are being developed all the time. I guess the challenge is for companies like Otoy to stay ahead of the curve.

Best,
Seeker