Two GPU's...only one uses Vram

[sirkaoselite]

Hi there, my first post as a licensed customer! I want to ask if it' s normal that octane uses only one Gpu for his Vram, i have two gigabyte gtx980 in SLI, each card have 4096mb of vram, the SLI is active and octane recognize two cards, here an image:

[glimpse]

Hi there,

everything looks normal or I should say as intended.

The scene should fit into vRAM of every GPU & thus no matter if You have one, two, three or., ten - You're always limited to active GPU that has smallest amount of vRam.

So if You use of of Your 4GB cards to power the monitor - that eats up ~300MB (at least), then other programs might use..- & thus Your available space will be less than 4GB, but more like a 3& half =) again, no matter how much cards You have =) the amount of VRAM is not adding up.

& P.S. Don't use SLI..it doesn't help & sometimes even cause some issues =) so it should be disabled.

[sirkaoselite]

Hi there,

everything looks normal or I should say as intended.

The scene should fit into vRAM of every GPU & thus no matter if You have one, two, three or., ten - You're always limited to active GPU that has smallest amount of vRam.

So if You use of of Your 4GB cards to power the monitor - that eats up ~300MB (at least), then other programs might use..- & thus Your available space will be less than 4GB, but more like a 3& half =) again, no matter how much cards You have =) the amount of VRAM is not adding up.

& P.S. Don't use SLI..it doesn't help & sometimes even cause some issues =) so it should be disabled.

Ok thanks!...so you suggest to disable the SLI in the Nvidia setings? It' s not almost the double of time saving with renderings? Because i bought those two gpu's for octane :')

[glimpse]

Ok thanks!...so you suggest to disable the SLI in the Nvidia setings? It' s not almost the double of time saving with renderings? Because i bought those two gpu's for octane :')

yes it should be disabled in nVidia settings (I don't know where that is =DDD)

but in order two use both card You simply tick the right boxes on CUDA devices in Octane & that's it =)
You'll be able render twice as fast with two cards, but Your vRAM will be limited (as mentioned before..)

[sirkaoselite]

Ok thanks!...so you suggest to disable the SLI in the Nvidia setings? It' s not almost the double of time saving with renderings? Because i bought those two gpu's for octane :')

yes it should be disabled in nVidia settings (I don't know where that is =DDD)

but in order two use both card You simply tick the right boxes on CUDA devices in Octane & that's it =)
You'll be able render twice as fast with two cards, but Your vRAM will be limited (as mentioned before..)

I haven' t understand precisely...you say that if i disable the SLI...octane will use better the CUDA of both cards? Sorry if i understand bad

[abreukers]

Hi sirkaoselite,

actually multiple cards together will add up the cores resulting in a linear speedup, unfortunately it is not same for the vram - memory is not compounded in the same manner in gpu renderers. All the textures and hdri among other stuff used for an entire scene has to fit into a functional swap space - that is each GPU must have a copy of all scene elements it needs to process - and therefore this swap space will be limited to the size of that card with the least amount of vram present in your machine. So if you use two 4gb 980 for rendering, the rendering is faster but the memory size used for the rendering is effectively only 4gb.

Also, SLI is mostly used for game applications to be able to work with separate video cards simultaneously to process very high frame rates between the cards and the CPU. Not necessarily for detection of gpus. Octane is rendering with the GPU (not the CPU) and Octane does not need SLI to detect the gpus installed in the machine. We don't recommend SLI for rendering, in fact, Octane will run much better without it.

hope this helps...