Should you mismatch your GPUs? NO.

[JimF_35]

I am posting this as a general information post. Some people think that if they buy a faster GPU for their system they can just leave their old one in too and it will take some of the load. This is wrong.

Please see these numbers:


GTX 780 and GTX 780

No SLI
- One Monitor Plugged into second card. -> Average FPS: 51.0 Score 1285
- Two Monitors Plugged into second card. -> Average FPS: 47.6 Score 1199
- Three Monitors plugged into same card. -> Average FPS: 51.1 Score 1287

With SLI
(With Span with surround)
- One Monitor Plugged into second card. -> Average FPS: 50.8 Score 1280
- Two Monitors Plugged into second card. -> Average FPS: 50.2 Score 1264
- Three Monitors plugged into same card. -> For some reason it would not let me because Windows kept getting screwed up with the "expand desktop to this monitor" function.

(No Span with Surround)
- Three Monitors plugged into same card. -> Average FPS: 80.2 Score 2020
- You have to have all monitors on same card for 3D Optimized.



GTX 780 and GTS 450

No SLI (Main Display set to GTX 780
- One Monitor Plugged into second card. -> Average FPS: 45.1 Score 1137
- Two Monitors Plugged into second card. -> Average FPS: 45.1 Score 1135
- Three Monitors plugged into same card. -> Average FPS: 51.4 Score 1296

No SLI (Main Display set to GTS 450
- One Monitor Plugged into second card. -> Average FPS: 8.2 Score 207
- Two Monitors Plugged into second card. -> Average FPS: 7.6 Score 191
- Card only had 2 DVIs

I could not SLI the GTX 780 with the GTS 450. I tried but no go just as I figured (Nvidia says you can't do this).

If you look at these numbers you will note that the GPU the system decides to use for all of its processing is the one the Primary Monitor is on. If you have your primary monitor on your slower GPU then your results will be really slow because it will not use your faster GPU at all.

It is better to put all of your monitors in your fastest GPU regardless of the case even with SLI and without. It is also better to not use surround SLI. My guess is with surround SLI that you're making a really big virtual monitor and that is why it is slower.



Summary:

Your system will only use one GPU at a time unless you have SLI or Crossfire and in order to do that you must match GPUS. I hope this helps you and others.

 

[smeezekitty]

This is not generally unknown information.
The computer uses the GPU the monitor is connected to for rendering. If you plug the monitor into the slow one, of course it will be low performance.

NVidia is very strict about SLI. You can only SLI the same model of card.
AMD is slightly more lenient about CF for example you can CF a R9-280 and an R9-280X

The disadvantage of mismatched cards is more stuttering.

 

[JackNaylorPE]

If you have two 7870s and a 450, the proper set up would be to put the two 780s in SLI (50% increased fps) and use the 450 for PhysX.

 

[JimF_35]

If you have two 7870s and a 450, the proper set up would be to put the two 780s in SLI (50% increased fps) and use the 450 for PhysX.

Exactly or just sell it.

 

[jitpublisher]

I thought this was pretty common knowledge, as both nVidia and AMD are very forth coming about what will work in SLI or Crossfire, and what will not. You can find that information just about anywhere from the motherboard manuals to the GPU manuals, to just about any site on line that deals with SLI or Crossfire. That is usually the very first thing they tell you.
You can use different Nvidia cards together in the same PC and dedicate 1 (usually the slower one) as a PhysX card if you want, and get some benefit in games that did rely heavily on PhysX.

 

[JackNaylorPE]

This should help you set up properly:

http://www.geforce.com/hardware/technology/3dvision-surround/system-requirements

GeForce GTX 780 2-way SLI With 2D Surround (Landscape)
> Orientation: Landscape
> Accessory Display: Yes, no additional GPU
> Maximum Resolution: 4800x2560
> Maximum Resolution (Bezel Correction): 6400x2560
> Maximum number of displays: 3 in Surround 1 Accessory Display

Special Instructions:
>Center Display of the Surround group should be connected in the left most card.
> Accessory Display must be connected to the card with the most number of displays.

One of 6 connection options

GeForce GTX 780 2-way SLI With 3D Surround (Landscape)
> Orientation: Landscape
> Accessory Display: Yes, no additional GPU
> Maximum Resolution: 5760x1080
> Maximum Resolution (Bezel Correction): 7680x1080
> Maximum number of displays: 3 in Surround 1 Accessory Display

Special Instructions:
> 3D Vision Surround requires using three DVI or three DisplayPort connectors.
> All monitors must be the same make and model for 3D Vision Surround.
> Using DisplayPort connectors may require the use of DisplayPort to Dual-link DVI adapters. Please consult your monitor's manual for supported 3D connectors.
> Center Display of the Surround group should be connected to the card with most displays.
> Accessory Display must be connected to the card with most number of displays.
> You can use any connector to enable the Accessory Display.

Option 1 of 6