OTOY Forums

Hi All,

I'm looking at getting a second GPU to speed up my render times with Octane and just wondered if anyone has any advice?

I'm currently running a GTX650Ti 1gb, windows 8 (64bit), core i5 2500k and 16gb RAM. and render times aren't exactly great.

I've been looking at getting a GTX 680 as it has 1536 CUDA cores. That along with my current 768 cuda cores in the 650ti - I thought this would make a decent set up...?

Does the GPU memory size relate to render times at all? Would a card with more memory render quicker?

I'm a bit of a novice with this stuff tbh so any advice would be greatly appreciated.

Thanks in advance.

As far as I know the amount of memory in the graphic cards only affects at how many textures you can handle in the scene. If the memory used by the textures is more than the available Vram the render will not start, so it doesn´t affect the speed of renders.

I would think it affects textures and geometry. However, in multi card setups, Octane only uses the amount of memory in your smallest card. So a 2gb 680 would increase the speed a lot, but not the size of scene you could render.

Keep your 650 and use it for display purposes. Select that in the Octane preferences by not having it active.
I think a GTX670/4gb is good value. Very nearly as fast as a 680, about the same price or cheaper, yet twice the data space for Octane.
Vram only matters for the scene - space for the geometry, textures and for the render itself - the amount doesn't determine the render speed. The render speed is basically down to the number of cuda cores available (including multiple gpu). Naturally how fast your gpu is clocked is a contributing factor.

pixelrush wrote:Keep your 650 and use it for display purposes. Select that in the Octane preferences by not having it active.
I think a GTX670/4gb is good value. Very nearly as fast as a 680, about the same price or cheaper, yet twice the data space for Octane.
Vram only matters for the scene - space for the geometry, textures and for the render itself - the amount doesn't determine the render speed. The render speed is basically down to the number of cuda cores available (including multiple gpu). Naturally how fast your gpu is clocked is a contributing factor.

That's not great news as far as my bank balance is concerned - getting a 4gb card suddenly shoots the price up massively.

I am actually beginning to regret my Octane purchase now as the extra cash outlay that's needed to make Octane a fast rendering solution seems a little out of my reach.

£250 for octane and lw plugin, £100 for a GTX 650 ti and now another £350 for a 4gb GTX 670. £700 for a GPU renderer is pretty steep imo. I probably should have done a little more reading before making my initial purchase.

I'm looking at getting a second GPU to speed up my render times with Octane and just wondered if anyone has any advice?

...I am actually beginning to regret my Octane purchase now as the extra cash outlay that's needed to make Octane a fast rendering solution seems a little out of my reach.

I'm pretty sure Octane is the fastest renderer per dollar cost, so I doubt you will get the same render speed anywhere else for less $.

There is a lot of performance to be gained from the render settings. Have you looked at using direct lighting, caustic_blur, hotpixel_removal, reducing maxdepth, using larger emitters, etc?

Paul

Yeh I have a GTX 580 and soon realised the limitation of 1.5G of RAM.

But the other way to look at it is that you don't need a new PC to speed up rendering in the future, a new graphics card is way cheaper than a new system. GPU's are getting faster at a quicker rate than CPU's.

That said you might eventually see an octane update including CPU support aswell, just like Iray does.

>That's not great news as far as my bank balance is concerned - getting a 4gb card suddenly shoots the price up massively.

Where I live a 670/4gb is cheaper than a 680/2gb you were already contemplating. I don't quite see your logic.
There is a lot you can do with this card in a practical sense. It is quite fast and has a decent amount of space. A card dedicated to display and another for cuda will make your system more responsive. I think you will be happy you made the upgrade.
Really there is no free lunch as far as obtaining render performance. Either you need to spend money on cpu or gpu. Gpu performance is easier and cheaper to add else you are networking whole new extra PCs. The cost of Octane performance scales with the cores and vram. Nvidia pricing pretty much has the bases covered, so that if you want 1.5x the speed you pay 1.5x the price etc. The 670/4gb is a good trade off IMO. At a later time when the cost/benefit is there you might add another 4gb card to halve your render time ( assuming you have the pci-e slots).
Remember people with a need for a maxed out render rig for archviz purposes are buying expensive mobo and then 4 GTX Titan/6gb for ~10x the money you are thinking of spending. They do this for commercial reasons and seem to be doing well out of it. HTH

These are all fair points but my budget is limited. I'm looking mainly at eBay as I'd rather avoid buying a brand new GPU. Currently a second hand gtx 670 is non existent so a full price one is nearly £400. I could pick up a second hand gtx 680 at half that but then only a 2gb version.

What kind of limitations would I be looking at with 2gb of memory? Sorry I know very little about this stuff- I've always rendered using CPU before.

Cheers.

Yup ok sorry didnt mean to be insensitive to that
I guess to answer that question well I should ask you what type of renders you want to do?
You can actually fit quite a lot in 2gb, a GTX680 might be quite ok for your needs