SLi isn't really "done" yet, so even in supported games it isn't really worth your money, you can get a much higher overall performance boost by either overclocking your card or buying one with more stream processors, higher clocked SP, or more memory bandwidth.
You can invest in an aftermarket cooling solution with some Arctic Silver thermal compound and do a simple volt-mod (usually involves drawing on a component with a standard pencil and measuring the result
http://www.vr-zone.com/content/6 ) and extract a lot of performance, this might not be your thing, but I have gotten 30-50% more performance out of several cards this way, none have died (gotta keep an eye on those temps and do proper burn-ins though, I use Arctic Silver always), and that is all that SLi can promise anyway, if you check out the reviews.
Keep in mind that the OC is always faster performance, some games don't benefit at all from SLi, or less than 10% boost, which is ridiculous for the outlay in an SLi setup.
I would either look into an overclock, or get a factory overclocked card (the top rung one, like the XXX Alpha Dog edition, or the SSC edition, I am unsure of the brand names since I do my own over-clocking). As far as a display goes the iZ3D is looking good if only for their stellar driver support of all cards (not SLi due to Mfg drivers being what they are, no dual output in SLi modes, or tri-/quad-output for that matter
![Confused :?](./images/smilies/icon_e_confused.gif)
), and had free shipping and a price equal to the Zalman at newegg.com this last week. I would of course like to try one in person, that doesn't seem like it will happen for me though
A side benefit of adding your own thermal solution is that many times it is quieter than the factory cooler, while offering better cooling, so you can leave it on high all the time and enjoy temps 20-30°C cooler than the OEM cooler on your card. It never hurts to have a 120mm Fan in the front of your case aimed at the PCI-E area and with all of the cabling routed out of the airflow as much as possible. I used a Scythe S-Flex unit and it isn't annoying or loud at all. I don't like case fans with tiny little holes to breathe through, so I cut out the restrictive grille when possilbe to allow all the air through the fan, it doesn't have to work as hard, is quieter and lasts longer as a result.