Hi. I was googling looking for help when I stumbled on your post. This card does NOT work in a dual monitor configuration with the QNIX 2710. I just spent the entire day trying to do just that. I have a EVGA GTX570 (old, 1280MB memory, dual dual-link DVI-I ports). It DOES work with dual QNIX 2710 monitors at 2560x1440. However, when I moved to my shiny new 4GB Gigabyte GTX 770 (from Amazon.com: http://www.amazon.com/gp/product/B00CU9GOAO/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1) I could get only one monitor to work. The monitor connected to the DVI-I port was not recognized. I bought my QNIX monitors on eBay. The listing very clearly said that it would work ONLY with DVI-D ports. That's true, at least with the Gigabyte 4GB GTX770 card.
Just thought I'd share my day of pain before you tried the same.
Andy, by the way, the monitors are GREAT! You have to be able to put up with a little backlight bleeding at the edge (in my case, the right edge of both monitors). But, the bleeding is really minor. For the price (I paid about $285 each!!) they're great. Here's the link to the ones I bought: http://www.ebay.com/itm/New-QNIX-QX2710-LED-Evolution-27-2560x1440-WQHD-PLS-Computer-Monitor-Matte-/121117252582?pt=Computer_Monitors&hash=item1c33269be6.
I've spent hours looking for a higher end graphics card to replace my GTX570 (one WITH dual DVI-D ports) and have yet to find one. Grrr...