Adding a 2nd graphics card

[rawdesigns]

Hey everyone I'm looking to upgrade my workstation PC and had a couple questions.

I currently have a Gigabyte GTX780 and would like to add another to help my render times and overall workflow. For best compatibility is it best to go with the same card? Also I was wondering if my power supply has enough juice to run the 2nd. It is a Corsair HX 750W (SLI ready).

Here's the links on the products thanks!

Geforce GTX780
http://www.newegg.com/Product/Product.a ... 6814125488

Corsair HX 750W
http://www.newegg.com/Product/Product.a ... 6817139010

[Oaktown]

Based on the power requirements for the GTX780 (http://www.geforce.com/hardware/desktop ... ifications), I would think that you'd want a 900W power supply to be safe.

As far as using a 2nd card with Resolume, here is a post by Joris in viewtopic.php?f=7&t=11242 a few weeks ago:

The heavy lifting is always done on the graphic card that has the GUI on it. This is why using multiple GPUs is not so efficient. Your output texture is calculated on the first GPU, and then needs to be copied over to the others. It's much more efficient to use a single GPU with multiple outputs or a graphic extender.

[Zerone]

I believe you would only need the same card if you need to run them in SLI

If you don't want to upgrade your power supply maybe check out the GTX 750ti
http://www.amazon.com/EVGA-Superclock-D ... B00IDG3IDO
i know they are low power consumption, i'm planning to possibly add 2x GTX 750ti's along side my 660ti that i currently have. so i can support multi outputs.

Also i move cards around some of my alt/smaller systems so possibly this solution works good for me having many cards rather than say 1 GTX 780.

I'm new to Resolume so trying to learn about this and optimal setups myself still.

[Warspite]

I just wanted to add another 3 outputs of Geforce640 to existing 4 outputs of Geforce 760.
And experienced fps drop from 60 to 35 when adding output on second video card instead of main card. May be there is some synchronization between cards, and one card is waiting for another to draw frame, do not know. Because fps drop was also dependent on what was connected to output - different refresh rate may also be the source of fps drop.

[Zerone]

I just wanted to add another 3 outputs of Geforce640 to existing 4 outputs of Geforce 760.
And experienced fps drop from 60 to 35 when adding output on second video card instead of main card. May be there is some synchronization between cards, and one card is waiting for another to draw frame, do not know. Because fps drop was also dependent on what was connected to output - different refresh rate may also be the source of fps drop.

What res are your input files and what is ur project output? I've been doing 2 outputs on a 660Ti plus control screen. i was planning on adding a 750ti wonder if i'll suffer the same issue?

If anyone with a little more experience could add to this. Also worried about sync issues that may be caused from this too

[dirtyjohn_lv]

Corsair recommends 1000W PSU for 2 graphics cards, they even have a handy tool
http://www.corsair.com/en-us/psu-finder

I use the AX2100i, because I have capture cards too.
Pushing the PSU closer to the limit will generate more heat, which creates problems in itself. Getting a higher wattage will help keep heat down.

I use 2 GTX780/780Ti in several servers (ASUS and EVGA cards) with no issues. It won't speed up render time, just give you more outputs. I constantly run 6 or more outputs at 60FPS with several layers of video.

I recommend the Windforce/ACX Cooler series, extra cooling for the graphics cards (my machines with the cooling series of cards actually run better than those without). My next step is to liquid cool everything and see if that helps performance

Using different cards could cause frame slow down, especially if the difference in cores/texture fill rate is significant, one card would have to lower it's rate to allow outputs to be synced.

Mixing cards with different architectures probably isn't a good idea (660Ti is Kepler, 750Ti is Maxwell).

[Oaktown]

Dirtyjohn_LV, what size composition and how many layers are you running when you get 60FPS on your machine with the two GTX780 GPUs?

[dirtyjohn_lv]

1920x1080 composition with 15 layers. I mix video on 3-5 layers of video and use other layers for routing to slices.

I also do capture of other VJs with the Vision DVI with no issues - I am able to output full 60FPS from them, just with a slight delay

You should also change your 3D settings for the cards. Set almost every option to performance mode (ambient occlusion, multi display, prefer maximum performance).

[Oaktown]

Great, thank you DirtyJohn_lv!

Have you ever had a chance to test with 3 GTX 780 GPUS on a P9X79 E-WS motherboard?

[dirtyjohn_lv]

I haven't had the need for that many outputs yet.

Save money and get the normal WS, the extra PCIe slot on the E is useless if you have a double wide card, covered by first GPU. I found this out the hard way after ordering 4 of them.