Using three gtx 970s in Rendering

I am a computer illiterate. A couple of my recent Blender projects crashed Blender because my 3 year old computer (Velocity Micro Edge Z40, i5-2320 CPU, 8 gig ram and a 1 gig gpu) was not powerful enough. I bought it specifically for Blender (I don’t play games). It has worked fine as I completed beginner tutorials. But I decided to build a new and improved computer.

I just purchased components for the computer build (my first). The components on the list below were recommended by others on different web site forums.

One of the issues I have is: What do I have to do to get the three gpus to facilitate and speed up work in Blender Cycles. I read several posts here concerning this, but I am still not sure what steps I need to take. In User Preferences -> System -> Compute Device -> I can now select CUDA and choose my GeForce GTS 450 from the drop down menu. What will I see in the drop down menu with my new build? Each GPU listed separately? All three combined? Since the gpus are all exactly the same in my new build, do I have to change anything in my BIOS when I’m working in three D mode and then when I go to render?

I’m not sure on your intial question i dont know how well blender would handle multiple GPU’s but looking at your build you’ve got 3 GPU’s and youve only got a 760w PSU. I would say you’d need 1000w minimum pushing that kind of hardware if not higher to be on the safe side. I’ve got a 750w running 1 GPU :stuck_out_tongue:

Well, I was going by expertise of those on the web site forum. When you pick your components on this site, you get a total estimated wattage at the top of your pick list. In my case, it came to 708.

Quite possibly the 760 W PSU can handle the three 970s + CPU + peripherals - but the question is:
Do you want to have your PSU running at over 90 percent of its capacity for significant amounts of time (= while rendering)? A beefier PSU might handle that load in a more relaxed way without permanently being stretched to its limits.

Ideally the continuous load should not exceed 85 percent of the PSU’s capacity (optimum: between 65 and 85 percent).

So: max 708 W from your components * 100 / 85 = min 833 W you’d need for the capacity of your PSU to have a system with a little room on the upside that doesn’t produce more heat and noise than necessary.

Additionally to whatIkariShinji said, keep in mind that if you plan to overclock your CPU/GPU at some point, they will use significantly more energy.

blender handles multi gpu’s nicely. tested up to 5 so far personally. But assume 200 watts per vid card unless you find a real figure…But for rendering Round up!!! rendering put a gpu under full load.

But if you want you can use a second powersupply just use one of these and run some vid cards on that.

<edit> for some of the latest and greatest vid cards, it might be an idea to assume 250 watts unless you can locate the real figure. just make sure and find out of it is measured in rms, average or peek power on both the vid card and powersupply.

5?! What kind of rig madness are you armed with?

Yes, you will see them individually and combined.

No not at all. You will have to download the latest drivers for them though, but you don’t need to do anything with the BIOS.

I’m glad I read your post. It started eating at me. I ended up returning the 760w for the 1200wi. I was thinking at the time 760w psu was kinda low when someone in another forum recommended it. To the others who posted here about this, thank you.