The Core 2 Quad and Core 2 Extreme are the most powerful CPUs in Intel’s line-up. As the name implies, Core 2 Quad processors all have four physical cores, while the Core 2 Extreme range includes one dual-core processor – the X6800 – as well as the quad-core QX6000 and QX9000 ranges.
Core 2 QuadThe Core 2 Quad range includes both 65nm and 45nm parts, based on the Kentsfield and Yorkfield cores respectively. Internally, they’re effectively a pair of Core 2 Duo processors built into one chip.
As AMD likes to point out, this is less efficient than the Phenom’s fully integrated design, as cores on different dies can’t communicate directly at the chip’s full internal speed. Instead, they have to pass data back and forth via the slower front side bus.
But in the real world, multithreaded programming is in its infancy and few applications use a quad-core processor like this. Far more often, the four cores will be running multiple independent processes in parallel, something the Core 2 Quad is perfectly equipped to do. It’s shrewd economics on Intel’s part to reuse existing core logic rather than investing in a completely new quad-core process.
The proof is in the results. The Core 2 Quad Q6600 costs exactly the same as AMD’s flagship Phenom 9600, but includes 8MB of on-die L2 cache, twice the total available to the Phenom. This helped the Q6600 achieve a storming 1.45 in our benchmarks, while AMD’s quad-core processor scored only 1.28.
In fact, in our tests, every Core 2 Quad processor easily outpaced anything produced by AMD. That’s partly down to bigger L2 caches (up to 12MB for the Q9450 and Q9550) and partly thanks to clock speeds that go as high as 2.83GHz on a 1333MHz front side bus.
Yet as a desktop processor, the Core 2 Quad range faces stiff competition from Intel’s own Core 2 Duos. The E8400, for example, achieved a higher overall benchmark score than the Q9300 in our tests, despite costing $80 less.
The extra processing power of the Core 2 Quad only shines through in properly multithreaded applications, such as our 3ds Max test: here, the E8400 took 206 seconds to render a scene that the Q9300 completed in 156 seconds. But if you’re looking for an all-rounder, the Core 2 Duo is better value.
Core 2 ExtremeIf, on the other hand, you’re after maximum performance, look to the Core 2 Extreme series. These chips are based on tweaked “XE” versions of the Conroe, Kentsfield and Yorkfield cores, running at clock speeds considerably in excess of their standard counterparts. The Yorkfield-based QX9770 goes as high as 3.2GHz, while the fastest Core 2 Quad with that core runs at 2.83GHz.
Core 2 Extreme processors are also fully multiplier-unlocked, so you can increase the clock speed as high as your motherboard will allow. There’s no guarantee that your CPU will be stable above its stated speed, but the appeal for enthusiasts is obvious.
The problem with the Extreme range is very apparent on our graph on page 60. It’s normal to pay a premium for top performance, but the Core 2 Extreme series takes that principle to absurdity. The Core 2 Extreme QX9650 costs over $650 more than the Core 2 Quad Q9550, for a performance boost of some 2%.
This month’s most powerful processor, the QX9770, will set you back a jaw-dropping $1878. Higher clock speeds may mean lower yields, but it’s hard to avoid the conclusion that Intel, knowing it has no competition in this area, has mercilessly set its prices to take maximum advantage of enthusiasts and number-crunchers.
So, despite peerless performance, it’s hard to recommend any Core 2 Extreme processor. If you absolutely must have the fastest processor on the block, it’s the only game in town, but you’ll pay through the nose for modest performance improvements over the Core 2 Quad.
In turn, the Core 2 Quad series suffers from a similar criticism in relation to the Core 2 Duo. If you can really make use of four cores then go ahead, but for everyday Windows computing the effective performance boost simply isn’t enough to justify the price increase over the Core 2 Duo E8000 series.
