People have had some time to play with the i7s a bit and figure out the various voltages and multipliers and relationships between them all needed to make them purr.
You can take a look here and here and see the reports from the trenches for yourself. Some progress is being made, the i7s seem to be a bit better than the initial reports indicated. Getting to 4GHz or a bit beyond seems to be fairly doable for the 920 overall, while significantly more than that seems possible for the 940 and especially 965. The 965 definitely seems to do better than its lesser brothers, and it should be noted that a large proportion if not most of those reporting results at the moment are reporting results from 965s. Given that the 965 costs a thousand dollars or more a pop, it’s very safe to say that the proportions of 965 to 920 users is going to change dramatically as people start buying these, so the average results will probably shift downward, too.
That being said, a consensus seems to be emerging that unless rendering or encoding is your life, there’s no reason to upgrade a good Penryn system for i7. On the other hand, for those well behind the curve building a new system essentially from scratch, more than a few have pointed out that if you’re going to load the new system for bear anyway (i.e. multiple video cards and more), an i7 system doesn’t cost that much more than a Penryn system.
What we don’t know, yet, is about the other contender. For the past couple years, the reality has been that no matter how cheap the AMD processor was, it was uncompetitive running at spec against Intel, and forget about any comparison with them overclocked. That picture may get a lot less ugly shortly. Fudzilla reports that they saw a Deneb in action the other day running at almost 4GHz on air. OK, a private screening under unknown circumstances isn’t exactly something most of you would take to the bank (even a bailed-out one), and you should be thinking, “Show me.”
But given that most people interested in i7s are more than inclined to wait until mobo and memory costs become less astronomical, and given that many of the hottest games are GPU-limited, and given that the overall AMD platform (especially the DDR2 version) may well end up costing a good deal less than the i7 or even Penryn platforms, maybe you ought to give Green the chance to show you.
True, Denebs are not at all likely to stand toe-to-toe with i7s even if they can hit 4GHz, but if they do, the comparisons won’t be as ridiculous as they’ve been in the past, and if you’re willing to forego some performance to save more than some money, this could be a good choice. Of course, this could very well not pan out: the CPU may not be able to overclock so much, or the price tag may not end up being so hot. But if the current price of an i7 upgrade gives you sticker shock, and that combined with the economy has kept you from pulling the trigger, maybe you ought to put down the gun until this target shows up.