The Good Major leap in performance on multitasking and most multithreaded applications compared to high-end dual-core CPUs; lots of apparent headroom for overclocking an already fast chip.
The Bad High price tag makes quad-core processing an elite technology for now; Apple's twin dual-core Xeons in the Mac Pro make for a faster digital design configuration.
The Bottom Line If you thought dual cores were over the top, get ready. Intel presents the Core 2 Extreme QX6700, a single CPU with four distinct processing cores. At $999, the first quad-core CPU will remain an enthusiast part for a while, but as a glimpse of the future, it's clear that clock speed is out and core counts are in.
Intel Core 2 Duo
Barely wrapped your brain around dual-core processors? It only gets worse from here, folks. Welcome to quad core, by way of Intel's Core 2 Extreme QX6700. Don't let the "Core 2" fool you (great job, Intel Product Naming department), this new chip has four physical processing cores in it that make it a multitasking beast. And if you're still stuck doing only one thing at a time on your desktop, the QX6700's promise for single-application performance is large, as well. We suspect that professionals and forward-looking gamers will be most interested in quad-core chips, and of the pros, the digital-media editors might not want to get rid of their Mac Pro's just yet. We found that with certain applications, Apple's high-end designer box is faster. At $999, the Core 2 Extreme QX6700 will likely end up in only the most expensive of desktops, but the fact is that the multicore revolution is fully upon us. You might not need a PC with such a pricey chip now, but our testing found that for applications and scenarios that will put it to the test, Intel's new quad-core chip will give you an absolute boost in performance.
We spared you the gory chip architecture details in our review of Intel's Core 2 Extreme X6800, and we're going to do the same here. The big news is doubling the number of cores to four; the rest of the chip architecture remains the same for the most part. If you must know all the ins and outs, we will refer you to our Alpha blog post that breaks down the bullet points. The key specs of the Core 2 Extreme QX6700 are its 2.66GHz-per-core clock speed, and its two separate 4MB L2 cache allotments--giving each pair of cores a 4MB pool to draw upon. That's, logically, twice as much cache as the dual-core Extreme X6800 chip. But if you've been paying attention to recent CPU developments, you might remember that the X6800 actually has a faster clock speed, coming in at 2.93GHz. Here's where multicore CPUs start to complicate our understanding of desktop processors.
If you'll recall, both Intel and AMD have been laying the groundwork to get people away from thinking of raw megahertz as the primary indicator of processor capability. The reason in a word is heat: The faster a chip runs, the hotter it becomes. When those Pentium Extreme Edition chips started hitting 3.6GHz and higher, the cumbersome liquid-cooling hardware required to keep them from overheating became a visible, noisy reminder that heat dissipation is a major challenge for system builders. Both AMD and Intel knew this before the Extreme Edition chips came to market, of course, but with the quad-core Core 2 Extreme QX6700, the answer to the problem becomes much easier to understand than even with dual-core CPUs; rather than make the chips faster, Intel has made them able to do more things at once.