Dual Monitors - One Graphics card vs Two

Question

I have a Dell Optiplex 790 with two Radeon HD 5450 cards (512MB Dedicated Memory) installed. Currently, I'm running two monitors off a single card.

Card 1-->HDMI Splitter-->Monitor 1
                    |---> Monitor 2
Card 2-->*Empty*

Looking in the machine itself, I cannot see any Crossfire bridge cable (I'm expecting an additional cable between the two cards), nor even ports on the cards to allow crossfire to be hooked up. Also, in the Catalyst Control Center I cannot see any checkboxes that allow enable/disabling of Crossfire (something I've read should be present when the cards are capable of being crossfired).

On that basis, I suppose I have two queries:

• First - Am I reading this correct that the cards are not Crossfired?
• Second - Is it more beneficial to run my two monitors from a card each, or is there no difference from running them both off the same card?

Answer 1

First - Am I reading this correct that the cards are not Crossfired?

To establish if you are using CrossFire, you should be able to do this from within the Catalyst Control Center, as you state yourself. Without that, you can safely assume that CrossFire isn't available at the moment, regardless of why.

Second - Is it more beneficial to run my two monitors from a card each, or is there no difference from running them both off the same card?

There's no noticeable difference, although in some cases with, say SLI, you'll be forced to setup a certain configuration of connected displays to actually use said technologies. For instance, with SLI (and CrossFireX), and a seperate-displays configuration, you connect your monitors to one card. That one card can be considered the "master", whilst the other card will participate in the rendering of frames and calculations - like PhysX-related computations.

It is worthwhile to mention a few of the typical requirements here:

• Amount of memory should be the same on all GPUs
  • Anything above the lowest denominator will not be used, as the memory is shared between all cards.
• All displays must be connected to the "master" card
  • This means that your secondary card - unless you're perhaps using NVIDIA Surround - will not have any displays connected. If displays connected to your secondary card work, then SLI/CrossFireX is not enabled.
• [SLI] The same GPU-series must be used, as it is dependent on the same architecture
• The data bus for your PCI express lane will be a deciding factor, so make sure you don't throttle your secondary card, as it'll reduce the performance.

Then, if you use NVIDIA Surround with SLI, you might be forced to employ a configuration like this.

Basically, depending on what features you use, the configurations you can employ will wary. To repeat regarding your question, I don't have accurate information on whether or not it could be, but whenever you're using CrossFireX or SLI, it is not possible to connect your displays to your secondary card, basically.