GPU Ram for Resolve 14

The recently published (18-08-2017) Resolve 14 Configuration Guide, page 37:

Some of the image processing operations in DaVinci Resolve, temporal noise reduction, optical
flow speed changes, motion effects and OpenFX plugins, also need large GPU memory for
operation and utilize a single GPU regardless of the number installed. These processes might
not be available or operation could be restricted on GPUs with limited memory so consider this
when selecting your GPU from the options below.

I appreciate the thorough detail of the Guide, it's invaluable.

Concerning the above limitation, the NVIDIA TITAN Xp supports the GeForce GTX SLI HB Bridge (as do GeForce GTX 1080 Ti, 1080, and 1070 cards). There are bridges for 2, 3 and 4 card setups. Is this arrangement "seen" by the processing operations as a single GPU?

Resolve does not use SLI at all, and in fact it should not be installed/enabled.

Hi.

I din't understand the No Sli, until I read Peter Chamberlain's explanation in this thread:

viewtopic.php?f=21&t=47660

It is at the end of page 1.

Regards Carsten.

I see, thanks Carsten. Peter Chamberlain explains:

Resolve does not use SLI or other cross GPU connections. We manage the GPUs directly.

I like this from JPOwens:

You will have a better chance of performance improvement if both your 'horses" are the same size that are pulling the same cart. Because the big horse will always be limited to what the small horse can do.

However, given that SLI (Scalable Link Interface) with HB Bridge (High-Bandwidth) is not supported, the image operations mentioned (temporal noise reduction, optical flow speed changes, motion effects and OpenFX plugins) are going to need a "big" GPU. The million dollar question (that probably can't be answered) is - how big? Currently the biggest are the nVidia Quadro P6000 (Pascal) @ 24GB. I assume that it's predecessor M6000 (Maxwell) will be phased-out.

Interesting thing about the nVidia Titans is that they are built with two GPUs with an onboard SLI....

[Peter Chamberlain]

Regardless, don't setup to use SLI. Resolve can use both GPUs.

You can install the SLI bridge, and in the Nvidia Control Panel you can enable/disable SLI as needed.

Make sure you also set Resolve Preferences on Hardware Configuration checked to Use Display GPU For Compute.

I switch between SLI and Non SLI all the time.

Hi David

If there is no SLI benefit in Resolve, I don't need it. The point was concerning operations that only use one GPU - If SLI was good for Resolve, if you really needed you could bridge up to 4 x nVidia 12GB Titans, which apparently in other software (games?) would essentially be seen as a 1 x 48GB card. Not many people would be doing that straight off - but it would mean that you could add to your setup if you experienced the failures described in the configuration guide, without wasting money.

Hi Peter

I think a guide or table that lists how much GPU Ram is required by the processes that only utilize a single GPU would be a great help. Without any quantification, how can we specify the right card?

Hi.

As I understand it was Resolves multi GPU function done before SLI. As I understand it do Resolve have benefit of multi GPU, it just don't use SLI.
It uses two GPU's to handle every second frame. And this is the reason two or more GPU's have to be of same type and with same amount of memory as explained very well by Peter Chamberlain in above link.

Regards Carsten.

Hi Carsten

That is perfectly true, but if you read my original post, it quotes from the Configuration Guide, Page 37:

Some of the image processing operations in DaVinci Resolve, temporal noise reduction, optical
flow speed changes, motion effects and OpenFX plugins, also need large GPU memory for
operation and utilize a single GPU regardless of the number installed.

Of course, since such operations always deal with multiple images, and they are faster if you can hold them all in RAM.

Hi Uli

That is certainly true. This is why I think a guide or table that lists how much GPU Ram is required by the processes that only utilize a single GPU is needed. We can then specify the right graphics card, but without blowing a hole in the budget unless necessary.

I would also love to know what is a safe level of VRAM for 8k red R3ds downsampled to either a QHD or HD TL... with temporal noise reduction (often separate nodes and qualifiers per colour channel)... is 11/12gb enough or 16gb or do we need to step up to 24gb? The challenge here is that I can have 2x 1080ti for the price of a p5000 (which is the only new card with 16)... or maybe all these cards are overkill and it is just the memory I need? It is easy to pick up a cheapish M6000 with 24gb.. is this a good way to go?

At the moment these operations are not always possible on 6k images with an old Titan (6gb) (I have a quadra for GUI) ... should I just extrapolate from the number of pixels processed or is there other factors I am not considering...?

Thank you

M

Ps when the next gen of cards come out will they have more memory or just faster?