Kind of always wanted a dual-gpu card, and finally getting one. Based on what I could find listed on Tom's Hardware, they put the 690 between the Radeon 7990 and the 295x2. Conversely, the cheapest 7990 was ~$150+, while what few 295x2's cheaper than $400 are usually "for parts" listings. And for $75, the 690 (with aftermarket cooling) seems like a deal. Don't even get me started on the Titan Z, of which a working example can still command over $700 even now.
While I wait for it to arrive, The thing I'm having trouble deciding is... once I make sure it works, which build do I put it in? Off the top of my head, I was thinking it would be a great overkill tier choice for a Windows XP machine, especially since SLI support was much more mature in that OS compared to Windows 7 or later. But it's also new enough to be pretty still well supported in 7~10, and support Shadowplay for encoding.
So, at present my choices in mind, where it'd make an appreciable impact, are either my Opteron build (s939 Opteron 185, 2GB RAM, presently a GTX 460 w/ Aftermarket cooler), my Pentium D build ( pentium ee 965 @ 4.26GHz, 8GB DDR2 RAM, presently Radeon 7770, Windows 10), or my Phenom build ( x4 965 @ 3.9GHz, 8GB DDR3 RAM, GTX 1050 presently, Windows 10). I'm certainly not above juggling parts if need be.
My opteron build is what I've focused on making into a Windows XP gaming machine primarily. And on a DFI LanParty board, it seems to make sense to give it the SLI treatment it was meant for. It would basically be the highest end GPU I could possibly get supported in a Windows XP installation, per my recollection.
Thinking about it, it would be a curious and appropriate thematic choice to use it in the Pentium Machine, since I named it Zweilous... given the lore about the pokemon whose heads constantly fight each other, and the 690 would fit that "dual headed" mantra.
Last but not least, the Phenom would be the closest to being in line performance wise with such a flagship level card. However, it's most likely to also conflict with the placement of the board's SATA connectors, which would limit how useful or usable it would be in that machine.
These are my thoughts on it, but I'd like to see what some might think.