Is it worth combining these GPU's?

V-Ray V-Ray Common Hardware
1

Hi guys;

It’s time to upgrade my GPU rendering machine.

My current system has a GTX 970 with a 750 Watt power supply.

I want to purchase 2 GTX 1080 Ti’s. To install them WITH the GTX 970, I’m told my 750 Watt power will not be enough and I will need a 1000W power supply. So there’s another $300 on top of everything. Or, do I just get rid of the GTX 970 and stick with the two GTX 1080 Ti’s.

I’m trying to keep as much rendering power as possible but is it worth spending the extra $300 to keep the GTX 970? Or will the performance boost combined with the 2 GTX 1080 Ti’s not be worth it?

Thanks in advance for your feedback!

-Rich

2

I would keep the 970 dedicated for display, so the 1080tis could render only.

Best,
Blago.

3

Ok, thanks Blago. So I’ll add the extra $300 for the power supply.

Is there any trick to installing drivers since I’ll have two different types of cards in there?

-Rich

4

When you download the driver, you’ll notice the “Supported Products” section on their site. You’ll see most cards use the same driver (same download file)

5

im wondering about getting a 1080ti, but isnt there a new ‘2080’ coming out soon? Unsure what the pricing/performance difference would be and if its worth waiting?

6

Will rendering with the GTX 970 and the two GTX 1080 Ti’s improve performance or will the GTX 970 present itself as a bottleneck? I know I’d be limited by the smaller amount of memory on the GTX 970 but would that be the only bottleneck?

Thanks,
-Rich

7

It will benefit a bit, but it will be really better to use it just for display, so the OS UI doesn’t lag while you render.

Best,
Blago.

8

V-Ray RT 3.6 Hybrid Mode with AMD Threadripper 1950X and NVIDIA Titan Xp

9

Blago;

One final question if you don’t mind as I am very close to buying (this week).

I need the most GPU rendering power I can get.

The option right now is to do what we discussed above which is keep my current GTX 970:

1X GTX 970 for primary
2X GTX 1080 Ti for secondary

or what I was leaning towards replace all the GPU’s with newer ones:

1X GTX 1080 Ti for primary
2X GTX 1080 Ti for secondary

I understand there is lag when using a primary card to render but I would set all three to render when I leave the studio for rendering overnight.

However, this benchmark is concerning: V-Ray RT 3.6 Hybrid Mode: Combining CPU and GPUs for Rendering | Puget Systems

The difference between rendering with 2X secondary GPU’s vs 3X GPU’s is minimal, it seems. Much less than there difference between two GPU’s.

Is it worth buying this third GTX 1080 Ti in this case? Again, I need the most rendering power I can get.

Thanks in advance for your reply.

-Rich

10

When you have adaptive rendering, the scaling in some scene might not be as linear. Usually you can alleviate that by setting higher “rays per pixel” values from the V-Ray GPU settings - this will make V-Ray giving bigger chunks of data to the GPUs, so they will be more utilised. It often helps a lot.

I can’t say for sure though, it is best for you to test and see how it works for you. Probably just get 2 x 1080ti and 1 x 970 for display, and if it is not as fast as you like, go for one more 1080ti in the future :slight_smile: ?

Best,
Blago.