AnandTech, Bit-Tech, FiringSquad, HardwareSecrets, Hexus.net, HotHardware, HardOCP (Gaming Performance / Music, Images, & Movie Performance / Power Consumption / Pricing and Specifications), NeoSeeker, TechReport, THG, TrustedReviews, TweakTown have an in-depth look at the performance of the Core 2 Duo E6400, E6600, E6700 and Core 2 Extreme X6800. Are the processors really as good as the previews said?

Bit-Tech: So then, it turns out that the performance numbers that we ran on the Intel-built Core 2 Duo E6700 system are as good as they looked the first time around. The performance capabilities of Intel's Core architecture are now clearer than ever. There wasn't a single test where the Core 2 Extreme X6800 fell behind AMD's current flagship processor - the Athlon 64 FX-62. Arguably though, the more intriguing processors are the lower-end Core 2 Duos, namely the E6600 and the E6400. There are many occasions where the Core 2 Duo E6600 is hot on the heels of the Athlon 64 FX-62, and in many cases Intel's slowest 4MB L2 cache Core 2 Duo outperforms AMD's flagship chip for roughly 1/3 of the price. On the other hand, there are many occasions where the Core 2 Duo E6400 puts in strong performances against the Athlon 64 X2 5000+ and X2 4600+ processors. In many situations, it came out on top of the X2 5000+ while costing considerably less than AMD's Athlon 64 X2 3800+.

TechReport: These processors consume less power-and thus produce less heat-than desktop Pentiums have for quite a while. The E6700 system's total power draw when fully loaded was 156 W, only 14W more than the Pentium Extreme Edition system drew while sitting idle. What's more, even the high-end Core 2 processors' power use was in line with that of the Energy Efficient versions of the Athlon 64 X2. That leaves room for many good things to happen, from less expensive cooling systems to quieter, smaller enclosures and even some righteous overclocking. Combine the low power draw with the performance we've seen, and the Core 2 is clearly the most energy-efficient desktop processor around. As much as I appreciate the performance and efficiency of these new CPUs, though, I can't endorse forking out a cool grand (minus one) for a Core 2 Extreme X6800. These top-end CPUs are always iffy values, even if they're insane performers. Meanwhile, the prices on the first two Core 2 Duos are very reasonable for what you get. At $316, the Core 2 Duo E6600 looks like a tremendous deal, provided you can get your hands on one. The E6700 is pricier at $530, but it'll beat the much more expensive FX-62 at almost every turn.

FiringSquad: What's AMD's response? In the short term, price cuts. We've been told to expect severe cuts on the entire Athlon 64 lineup later this month, including AMD's latest AM2-based X2 CPUs. Later this year AMD plans to introduce faster X2 and FX CPUs, while AMD's also hard at work on their dual-core, dual-socket platform for enthusiasts codenamed 4x4. The 4x4 connotation indicates AMD's plans for the platform to roll over anything that gets in its way, including Core 2 Extreme. If it's able to pull this off is anyone's guess at this point, and you can expect that any dual-socket, dual-CPU platform isn't going to be cheap. AMD's true answer to the Core 2 family really won't come until their upcoming K8L core debuts next year.

Ed.note: The reviews makes it clear that Intel is the new king of not only processor performance, but also performance per watt. At $316, the Core 2 Duo E6600 looks to be a particularly nice deal, while the $999 Core 2 Extreme X6800 offers unrivaled performance for a desktop processor!