Judging just the processor alone, the Core i7 920 delivers excellent performance at a respectable price range of about $250 - $300. Even at stock speeds, it's a pretty good value, but when you throw overclocking into the mix, the 920 becomes a much more attractive option. Suddenly, with a little work, you can get substantially higher clock speeds compared to what Intel has on the market today, heavily outpacing the $1,000 Core i7 Extreme Edition chip at 3.2 GHz. This translates to a huge amount of computing power at a very low price.
However, when you factor in the entire platform upgrades needed to move to the Core i7, things get slightly less exciting. In order to move to the new CPU, you need an X58 motherboard, which can run from $275 - $350 in most scenarios. If you don't have DDR3 memory, moving to a new 3GB or 6 GB pack (for triple-channel memory support) can add another few hundred dollars on top of that. If you want to really overclock, you'll want a third party cooler too, which can lop on another $50. Things quickly add up in this new territory, but overall, most can make the move to the Core i7 for under $750 total in most scenarios.
At 4.0 GHz clock speed, the Intel Core i7 920 delivers a great computing experience. While it's tough to tell a difference with small tasks at the stock speed of the 2.66 GHz Core i7 920 processor, the difference in heavy application and gaming performance was immediately noticeable. The system felt slightly snappier overall, although considering the Core i7 920 chip is already pretty fast as is, you'd likely only notice the differences when you really start to tax the system.
However, as a "free" upgrade, there is no denying overclocking is a good value. With a nice third party cooler, you can still keep the chip cool and quiet, even at these higher clock rates. If you have a good motherboard with proper memory module support, you can make sure your clock speeds and timings are in-line, leading to very little chance of system instability. Getting the chip up and running at fairly high frequencies is quite easy to do, as well, if you know exactly what to tweak and by how much. Even though a lot of things have changed about the Core i7 platform compared to the Core 2 series, the overall overclockability of the chips haven't changed much. In fact, these first Core i7 chips appear to be overclocking surprisingly well so early on after its debut, which is great for first-round buyers.
Even better, the higher-binned Core i7 processors, the 940 and 965XE, are overclocking exceedingly high, as well. While the Core i7 920 is definitely the value leader, throwing a few hundred dollars here or there might allow you to push past 4.0 GHz a little easier compared to the 920, although we doubt you'll get that much more to justify the price tag increase. We're also now starting to see the first wave of less-expensive X58 motherboards hit the market, hoping to crack the sub-$300 price point. In addition, DDR3 memory prices are becoming more reasonable every day, so it looks like a pretty solid time to make an upgrade move, especially if you're mode of burning off all those holiday gift cards.