Introduction

Last July, Intel shook up the CPU world with the debut of their Core 2 line of processors. With its more efficient 14-stage pipeline, wider execution core, completely unified advanced smart cache, and other improvements, Core 2 took CPU performance to another level; in some cases Core 2 delivered a performance improvement of nearly 2X over the fastest Pentium Extreme Edition processor. No one outside of Intel expected Core 2 to deliver this kind of performance – including AMD.

Since launching Core 2, Intel has gone on to introduce quad-core variants of many of these processors -- the Core 2 Quad Q6600 for instance essentially fuses two Core 2 Duo E6600s on one package. Intel also trickled Core 2 down to lower price points earlier this year, the Core 2 Duo E4300 and E4400 are both popular choices for enthusiasts on a strict budget. But fundamentally, little has changed with Core 2 from a tech perspective: at 2.93GHz, the 1-year-old Core 2 Extreme X6800 is still one of Intel’s fastest processors for gaming.

But all that is about to change.

Starting with today’s arrival of the Core 2 Extreme QX6850, Intel will be tweaking Core 2’s architecture for more performance. As we noted in our Core 2 Duo E6750 Performance Preview article, Intel is equipping its latest Core 2 CPUs with a 1333MHz FSB. This change nets an additional 20% in peak memory bandwidth going to the CPU.

Why is this important? Because as Core 2 scales to clock speeds beyond 3GHz, the CPU pulls further away from the system bus in bandwidth. It’s important that the system bus is fast enough to keep the CPU fed with data. The system bus also plays a crucial role with today’s quad-core Core 2 processors, as it’s the system bus that is responsible for linking the two dual-core die together.

The Core 2 QX6800 (left) QX6850 (right)

The Core 2 Extreme QX6850

In the case of the Core 2 Extreme QX6850, you’ve got four processing cores running at 3.0GHz with a 1333MHz FSB (9.0x333). While it’s sitting on a 1333MHz system bus and running at 3.0GHz, its power consumption is similar to the Core 2 Extreme QX6800. You can also see that the QX6850 continues to rely on Intel’s LGA-775 socket and looks practically identical to Core 2 CPUs launched last year.

Although the Core 2 Extreme QX6850 is compatible with the LGA-775 socket, officially the only chipsets that are 100% compatible with Intel’s new 1333MHz FSB CPUs are the recently released Bearlake family (including the X38, P35, and G33 chipsets) and NVIDIA’s nForce 680i platform, which just requires a BIOS update to support the new processors. In fact, all of these chipsets are also designed to support Intel’s upcoming Penryn CPUs as well.

Officially motherboards based on the 975X and P965 chipsets don’t support 1333MHz CPUs.

In addition to the Core 2 Extreme QX6850, today Intel is launching three additional 1333MHz FSB CPUs: the Core 2 Duo E6550 running at 2.33GHz, the 2.66GHz Core 2 Duo E6750, and the Core 2 Duo E6850, which runs at 3.0GHz. Intel is also pulling the wraps off a new 1066MHz FSB quad-core CPU, the Core 2 Quad Q6700. The following chart outlines all the info on the new CPUs:

Intel's Latest Core 2 CPUs
CPU	# of Cores	Clock Speed	Front-side bus	L2 Cache	Price
Core 2 Extreme QX6850	4	3.0GHz	1333MHz	8MB	$999
Core 2 Quad Q6700	4	2.66GHz	1066MHz	8MB	$530
Core 2 Duo E6850	2	3.0GHz	1333MHz	4MB	$266
Core 2 Duo E6750	2	2.66GHz	1333MHz	4MB	$183
Core 2 Duo E6550	2	2.33GHz	1333MHz	4MB	$163

As you can see, the new processors are coming with significant price cuts: bulk pricing for the E6750 is listed at just $183, that’s $133 cheaper than the price Intel was selling the Core 2 Duo E6700 for previously! Speaking of the E6700, we’ve been told that Intel will be revising their pricing for it, as well as the other Core 2 CPUs, sometime next week. As far as availability of the new CPUs is concerned, we’ve been told that the processors are shipping to OEMs now, with retail availability in the next 2 weeks.

Overclocking

Armed with the same ASUS P5K3 Deluxe and Kingston KHX11000D3LLK2/2G DDR3 memory modules we used in the E6750 article, we were eager to see how far we could push the QX6850. This time we elected to use a Scythe Infinity heatsink/fan unit for maximum cooling.

Once again we nearly hit the 4GHz mark, as the QX6850 OC’ed to 3.81GHz at 423MHz FSB. At that speed we needed 1.4875V to ensure maximum stability.

3.81GHz

We could actually get the CPU to run in Windows at higher speeds, but stability was iffy in some benchmarks. 3.81GHz was the highest speed that was capable of completing all our benchmark testing.