Intel Core 2 Extreme QX6850

Intel's latest high-end, quad-core chip, the Core 2 Extreme QX6850, nudges past its QX6800 predecessor rather than taking a significant a leap forward. Moving from a 2.93GHz clock speed to 3.0GHz didn't result in tremendous performance gains on our benchmarks, nor did the switch to a faster front-side bus. Instead, the major appeal here is the price drop. For $999, Intel's new chip delivers performance that's on par with its older, much pricier QX6800. Just know that AMD and Intel each have new product lines coming out by the end of the year that might prove worth waiting for.

The 3.0GHz QX6850's progenitor, the 2.93 GHz Core 2 Extreme QX6800, was actually not that widely available as a standalone product. If your PC has one, chances are it's because you purchased a complete system from a high-end system vendor. Still, with a suggested price of $1,200 and a street price of $1,350 at the time of this review, Intel's previous top-dog chip sat in a new category of expensive for high-end CPUs.

For motherboards, the QX6850 uses the same LGA 775 design as its current generation of dual-core and quad-core CPUs, which means that you don't necessarily need a next-generation motherboard to use it. But unless you go with certain Intel G33, P35, or X38 chipset-based motherboards, or a BIOS-updated Nforce 600-series board from Nvidia, you won't get support for the faster 1,333MHz front-side bus. We used both Asus P5K and P5K3 motherboards for our testing, both based on Intel's P35 chipset, but the latter using the newer (and much pricier) DDR3 RAM.

As you'll see, neither the new chip nor the faster memory subsystem delivered major performance gains--at least today. The absence of otherworldly performance is offset by the QX6850's earthly price, however; at $999, the QX6850 makes the case for a high-end part to bridge the gap until AMD's and Intel's next-gen quad-core parts make their debut at the end of the year.

As our test results reveal, the QX6850 doesn't actually give you that much more performance out of the box compared with the QX6800, even (as we suspected) when we paired the new chip with faster DDR3 SDRAM. Our custom multimedia test, which performs a QuickTime movie and iTunes MP3 conversions simultaneously, shows the largest margin in favor of the QX6850, but even the 17-second difference doesn't fall outside of our 5 percent margin for error. We didn't expect a significant difference between two chips with such similar clock speeds, even when you factor in the QX6850's speedier front-side bus (1,333MHz compared to the QX6800's 1,066MHz limit). Because the newer chip delivers equivalent or better performance for about $350 less than the older model, however, its advantages pretty much speak for themselves.

If we have reservations about purchasing Intel's new CPU now, it's that Intel has a next-generation chip architecture--code-named Penryn--coming out at the end of the year. We don't know the full details of its launch products yet, but we do know that among the new features, Intel plans to add an updated set of multimedia instructions, called SSE 4.0. Penryn also marks Intel's move to a new, 45-nanometer manufacturing process, which means lower operating temperature and, thus, room for faster clock speeds. AMD will also likely have launched its own quad-core desktop chips--code-named Barcelona--by that time as well. At the very least, we'd wait to buy the QX6850 until the Intel X38 motherboards become available (later this quarter), as they'll introduce wider graphics bandwidth via the new PCI Express 2.0 interface.

Multimedia Multitasking Test
(Shorter bars indicate better performance)

In seconds

Intel Core 2 Extreme QX6850 (1,333MHz DDR3)

452 

Intel Core 2 Extreme QX6850 (1,066MHz DDR2)

453 

Intel Core 2 Extreme QX6800 (1,066MHz DDR2)

470 

CineBench
(Longer bars indicate better performance)

Rendering Multiple CPUs

Rendering Single CPU

Intel Core 2 Extreme QX6850 (1,333MHz DDR3)

1607 

507 

Intel Core 2 Extreme QX6850 (1,066MHz DDR2)

1605 

506 

Intel Core 2 Extreme QX6800 (1,066MHz DDR2)

1554 

493 

CPU-limited Quake 4 (in frames per second)
(Longer bars indicate better performance)

800 x 600, low-quality, no AA/AF

Intel Core 2 Extreme QX6850 (1,066MHz DDR2)

156.5 

Intel Core 2 Extreme QX6850 (1,333MHz DDR3)

156.4 

Intel Core 2 Extreme QX6800 (1,066MHz DDR2)

149.1 

Editor's note: Thanks to Asus who provided the motherboards and loaned us the Corsair DDR3 memory for this review's performance tests.

Test bed configurations:

Intel Core 2 Extreme QX6800 (DDR2 1,066MHz)
Windows Vista Ultimate; Asus P5K Deluxe motherboard with Intel P35 chip set; 2GB Crucial Ballistix Tracer 1,066MHz DDR2 SDRAM; 512MB ATI Radeon HD 2900 XT; 74GB Western Digital 10,000rpm Serial ATA/150 hard drive

Intel Core 2 Extreme QX6850 (DDR2 1,066MHz)
Windows Vista Ultimate; Asus P5K Deluxe motherboard with Intel P35 chip set; 2GB Crucial Ballistix Tracer 1,066MHz DDR2 SDRAM; 512MB ATI Radeon HD 2900 XT; 74GB Western Digital 10,000rpm Serial ATA/150 hard drive

Intel Core 2 Extreme QX6850 (DDR3 1,333MHz)
Windows Vista Ultimate; Asus P5K3 Deluxe motherboard with Intel P35 chip set; 2GB Corsair XMS3 DHX 1,333MHz DDR3 SDRAM; 512MB ATI Radeon HD 2900 XT; 74GB Western Digital 10,000rpm Serial ATA/150 hard drive

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