No GPU usage for Cuda

[Robert Lee]

Hi,
I just downloaded the latest version to try out on the following specs:
Quad Intel 3GHz
8GB DDR3
300GB Raptor
GTX280
SU v8
Vista Business x64 SP1

When I do a test render, according to MSI Afterburner, the GPU just hoover around 8% or 9% so I know its not using the GPU, because when I ran the Fur test or 3DMark, the GPU will hit 95-100% all the time.
According to the Rendering Settings on Indigo, the boxes for Cuda are checked and Cuda version listed as 4.2, but strange enough, even though they are all checked, all the boxes are greyed out.
I even went as far as uninstalling Indigo and nVidia drivers and then reinstalled the latest nVidia drivers again before reinstalling Indigo.

Am I missing something important or some settings or even the wrong hardware ?

[CTZn]

Installing the latest drivers was a good move anyways. The mode and gpu parameters can not be changed while rendering.

Indigo is using the GPU but in conjunction with the CPU: it's not a pure GPU implementation but an hybrid method. The CPU is required to handle some data wich wouldn't fit into the GPU pipelines. A faster CPU would be the way to have the GPU used more by Indigo.

The CPU is the bottleneck currently, the slower it will be the more the GPU will be idling. We can expect Indigo to be evolving with GPU technologies.

[Robert Lee]

Hi, Thanks for your reply.
Please excuse my limited understanding of Indigo, but are you saying that even with a Quadcore Intel 3GHz, it is still not fast enough to make Indigo work as it should ?
I would imagined that a Quad would be classed as a medium to high end CPU, the only reason why I am testing Indigo is it said it would uses Cuda technology to take over most of the workloads, but even as is now, it doesnt even uses more than 10% of the GPU at anytime. I have to say, the GTX280 is a bit old at almost 3-4 years, but its raw performance still outshine a lot of the newer cards, so I am a bit confused by this one.

[CTZn]

That's because the tasks handled by each part (CPU and GPU) are different in nature.

Your GPU is indeed 10 times faster at handling his own kind of highly specific tasks than the CPU is at handling all the rest.

For instance, I own a GTX260. When it is used by Indigo, the gain from the GPU in term of performances is about 30% (more samples per seconds). That's how we quantify the acceleration provided.

[lycium]

Hi Robert,

As CTZn mentioned, Indigo uses a hybrid acceleration approach for rendering with GPU. This means the GPU shares some of the CPU's workload, which allows for broad feature support and using a lot less GPU memory compared to purely-GPU approaches.

The downside is that when the GPU is much faster than the CPU, as it seems to be in your case, the CPU can't feed the GPU with work fast enough!

Regarding processor speed, some Intel quadcores are 5 years old already (amazingly!) such as the Q6600, and they have been far surpassed in performance by more recent quadcores, such as the Core i7 range introduced in late 2008. We've found these work very well with the 4xx and 5xx generation GeForce cards such as yours.

[PigsOnTheWings]

Noticed this as well for AMD HD7950. During pathtracing its a bit limited by the CPU. But the speed gain is really great anyways

I'm getting 8-9% core usage from Indigo, and when running LuxMark with CPU+GPU hybrid, I get the same result (10-11%)

[Pibuz]

Regarding processor speed, some Intel quadcores are 5 years old already (amazingly!) such as the Q6600, and they have been far surpassed in performance by more recent quadcores, such as the Core i7 range introduced in late 2008.

HEY! DON'T TAKE OFFENCE TO MY Q6600!

[lycium]

Regarding processor speed, some Intel quadcores are 5 years old already (amazingly!) such as the Q6600, and they have been far surpassed in performance by more recent quadcores, such as the Core i7 range introduced in late 2008.

HEY! DON'T TAKE OFFENCE TO MY Q6600!