buying a 1080 for workstation now that we have 3.6 and hybrid rendering

[coolhand78]

Just wanting some advice on how hybrid rendering works in relation to the gpu...

I currently have an i7 5930 with 32Gb RAM and an Asus GTX970 Strix GPU.

I'm wanting to upgrade to a 1080 in order to speed up my test rendering, here we do small test renders (say 1000px) and then send off production size images to the render farm (>4961px).

what i'm really wanting to know is when looking to buy the new card should is the memory (eg. 8Gb) of the card the deciding factor as to how it will perform when rendering?
and is 8Gb resonable?

also would i be able to use both my 970 and 1080 combined with the i7 for even more rendering power?

sorry for the noob questions, but I'm grateful for the advice.

[Svetlozar Draganov]

GPU memory size is one of the main factors for the rendering actually. It determines the complexity of scenes you are about to render.
Less memory will allow you to render small to medium scenes, complex ones will most likely to crash cause of insufficient memory.

Reasonable memory size is something very subjective and it depends from the scenes you are about to render, it's best to run some tests with the existing GTX970 and see what's the GPU memory consumption of the most heavier scenes you have.

Please be informed that when you have two GPU cards with different memory size, the smaller one will determine the memory that V-Ray will be able to utilize. If more memory is required for the rendering and such is available on one of the card but not for the other you'll get a warning about insufficient memory and the render will stop.

You will be able to use all devices including the CPU simultaneously.

[savage309]

Also, V-Ray GPU does not use additional GPU memory for the frame buffer when doing larger resolution renders and/or for having many render elements. Many clients are using 1080ti - on top of the 3GB additional memory it is 30 to 40 percent faster compared to 1080.

Best,
Blago.