Using two different video cards for Cycles

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1

Hello!

I am about to update my computer for faster rendering in Cycles :slight_smile: I am currently using a single GTX 560 Ti. When GTX 680 was announced I was planning to get those but since Nvidia has capped them I will get the GTX 580s instead.

Now to my question; since I like my GTX 560 Ti very much and would like to avoid selling it/throwing it away, could I just add an GTX 580 to my rig for an extra 100%+ speed in rendering or do the cards have to be identical?

So, is a GTX 560 Ti 1GB + GTX 580 1,5GB possible? (I suppose I can only use 1GB of VRAM if it works)

Or do I have to get 2 GTX 580s?

(My rig supports SLI and I have a 750W PSU, which I hope is enough)

2

SLI should work for those cards since they’re in the same series, but Cycles should be able to use both cards whether they’re in SLI or not.

It’s your power supply that I’m concerned about. You’re right on the edge of the recommended wattage.

3

Great! Just what I wanted. I know you have to have identical cards for SLI gaming etc, but what I really wanted to know was if it matters when dealing with GPGPU like activities :slight_smile: And I take it as a no then.

I tried to fill in everything I could about my computer and at 100% peak load it drew 747 Watts. Gotta live on the edge someimes :eyebrowlift: But at 90% load it was at 677 Watts, a pretty safe number to me. The question is, can I ever, ever reach a 100% load? I filled in all harddrives, fans, usb stuff etc etc. It feels like it never should reach the maximum.

But do you think it is stupid to try? I did buy a quality PSU though (not some random cheap brand that claims 750W) just to be sure that it would hold up to the most.

4

Never mind the PSU problem. I just found a great product, Add2PSU so you can have multiple PSUs :slight_smile: So I can buy another one and use that one on a couple of the graphics cards!

I still wonder what happens in Cycles when you graphics cards have so different amounts of memory though. Is it pointless to have a couple of 3GB cards if I also have a 1GB card? Will everything be capped to suit the worst card or how does it work?

5

I have been given a geforce 9800 gtx, can i use it with my geforce gtx 570 for cycles? my psu is coolermaster 650w. I’m not a great at tech so would appreciate advice :slight_smile:

No idea what SLI or crossfire is ;/

6

Check the manufacturers website to see the listed wattage consumption under full load. That mean CPU + GPU/s + Monitor + Everything else that eats watts in your computer setup + at least 100 watt relief space = how much your PSU should be.

Note that PSUs ( especially 80 plus Gold certified ) are a blessing with energy consumption when you are at 50% load ( that’s when they are most efficient )

7

Thanks, I checked the info that i could find, ran it all through the above link (adding a few extras to be sure)

You’re right on the edge of the recommended wattage.

and got = min 623w / recommended 673w. My PSU states output capacity 650w and max output 780W. It’s a bronze psu with best efficiency at 85%. So part of me thinks I could ‘get away’ with it, and the tiny sensible part of me says ‘no’.

So now i’m kinda hopeful but not so sure :slight_smile:

8

Keep in mind also that any PSU will only be running at 80% of it’s INITIAL efficiency after 12 to 18 months. So, if it was 80% efficient to begin with, after a couple of years, it’ll only be 64% efficient compared to it’s out-of-box specifications.

9

so, out of interest, what happens to an overloaded psu? auto shutdown or explodey type effect?

10

<nightmare>
They may turn into flames and fry the rest of your Hardware with it. Worst case your House burns down while that happens in a nightly rendersession :smiley:
</nightmare>

11

oh okay… is that a bad thing? :stuck_out_tongue: