I've been looking at cards such as the AMD 7770 as an update to my htpc system. It'd be of great interest to see how these and other lower end and/or passive cooled cards measure up in comparison to the IntelHD 2500 or 4000 integrated graphics on Ivy Bridge chips. Really, I can't see myself or anyone else buying a 6*** series card, comparisons there are likely of use only to people who already use one. But it'd be nice to know what sort of performance increase to expect of a card in comparison to that on an IB i7 for example, or rather how much of a gfx card boost is needed to make it worthwhile.

Worthwhile for what? Unless you state a use, there's no way to compare.

Good point. I was thinking of using the htpc for some games, as a social thing. I can play Civ V on my main machine with a 7850 and 27" monitor, but have also found that some older games work OK on the i3. Perhaps just as a rough metric, since we're dealing with DX11 devices, how about running the Heaven benchmark and 3DMark11? I realise how that can look, no I don't want a graphics card so I can run benchmarks on it, but to get a sense of how fast a card is. 'Worthwhile' then, would be some noticeable increase in performance, which would hopefully translate to acceptable framerates.

Ah, gaming.

You can do some basic gaming with the HD4000 IGP. There are plenty of Ivy Bridge release reviews out there to get a feel for what the IGP will do. At best, it'll be somewhat playable at 1366x768 with image quality (AA, AF, etc) dialed down. Haswell, next year's CPU, should double the fps.

When you move to a discrete card, here's the stuff to think about:
- what's the monitor resolution? (in your case, with an HTPC, the assumption is 1920x1080)
- what are the games? (Some are GPU intensive, some are CPU intensive)
- How much bling (AA, AF, etc) do you want turned on? This can make a staggering difference on $'s spent.
- How much do you want to pay?
- And since this is SPCR:
- how quiet do I want the card to be?
- how much power does it use?

Then go look at the latest reviews. They'll all show benchmarks of a variety of games vs a dozen or more different cards.

The short version for 1080p gaming:
low end ($200-240): HD7850, GTX 660
high end ($300): GTX 660 Ti

This generation, I like the Nvidia cards over AMD due to lower power use in 2D, BluRay, multi-monitor uses.

The 7770 is an excellent choice. It is a noteworthy card here because it's probably the highest end card that can be cooled passively with the right choice of cooler.
http://www.tomshardware.com/reviews/gam ... 107-7.html
each 3-4 tiers probably represents a doubling of speed. There is still a chasm in performance between the HD4000 (I put up with it for a while) and a 7770 especially at 1080p