GTX460 wastes 50Watts more with 2 displays connected than with 1 only, GTX560 probably too. There is Nvidiainspector software that enables 2d mode with 2 displays, problem solved in windows.
If what you say about NVidiaInspector is true, then this is indeed relevant to my interests. When you say "2d mode", what does it entail? Quite often I'm running a 3d app that shouldn't need to stress the GPU constantly, but might be problematic with such a setting...
I found this thread
where it is mentioned that NvidiaInspector does have problems still if you use two screens with different resolutions / refresh rate... I've read elsewhere (ref http://www.legitreviews.com/article/1461/19/
, via bit-tech forum
) comments that the cards would downclock (without needing special software) provided identical displays were used, but that different displays even with similar specs would not.
If you run two different monitors at the same resolution it won't keep the video card at idle as each monitor has different internal timings and the card will run at full load.
I could get another EA231WMi to match what I have, but I was hoping to get something different (currently erring towards Dell ST2220T for debugging touchscreen stuff and also taking up less room). It seems that expecting two different displays with the same resolution / refresh rate to allow the the card to reliably downclock would be wishful thinking.[/edit]
As for quicksync, ssd caching, virtu and overclock the benefits are questionable and pure marketing bluff. It is not guaranteed to work the way you expect it to. So i'd get H61 chipset for 60$ and wait for better chipsets next year and get SSD standalone, not for caching.
You might be mistaking me for the sort of person who will significantly change my setup on a yearly basis... also, did you mean H67? 
I clearly haven't been paying full attention; missed H61... don't think I want to get something that I'd plan on changing soon anyway, but thanks.[/edit]
I agree with you to an extent about marketing bluff; however, it seems like people manage to get pretty substantial overclocks without massive effort and I still feel that the IGP might have some other GPGPU potential beyond QuickSync, although it is admittedly not totally clear whether or not that is the case or whether I will really end up reaping it. Clearly SSD standalone will be better for performance, and I had been toying with the idea for a while but I think I'm going to hold off SSD altogether for now anyway. As I've said, SSD cache seems like it could be a reasonably sound approach, but never as fast as standalone and I don't understand why it should be marketed as a motherboard chipset feature; seems like the job of an operating system, but what do I know?
It does seem quite likely that Virtu won't ever be ideal, and it is still a bit early to tell really.
Those 6-chipsets are overpriced and use old tech 65nm. that is 2 generations away from CPu tech. it should have been at least 45nm, and next gen must have been 32nm chipset, they are clearly lagging behind the minimum acceptable, now the chipset is 2.5 times bigger, and 2.5 more expensive to make and motherboards are overcumbered with pointless stuff. No USB3, PCI-legacy still persists. If it is no problem for you go ahead with Z68.
I think I will go ahead with Z68. I'm starting to think an mATX board might be adequate for me; it seems I can get something with the features (including USB3, FW and most likely no legacy PCI) I want for about £110-£130. I'm not really a hardware person, and must admit I find the relationship between fabrication process of motherboard chips and what I want to do with my machine somewhat tenuous.