Review At the beginning of November Intel launched its four-core Core 2 Extreme QX6700 processor, where the Q, of course, stands for 'quad'. This Extreme processor has an unlocked multiplier so we reviewers can have fun experimenting with a £650 piece of silicon while the buying public regards Extreme products as a technological showcase and waits for the mainstream versions to arrive...
By that token the Core 2 Quad Q6600 is a really big deal as it is the first retail quad-core processor to target the mainstream desktop market and to ship with a locked multiplier. But other than that it's very similar indeed to the QX6700. Well, OK, the clock speed is one bump lower, at 2.4GHz, hence the model code, as the Q6600 is effectively a pair of Core 2 Duo E6600 cores on a single socket with a pair of 4MB L2 caches and a 1066MHz frontside bus.
Intel reinforced the message that this is the quad-core processor for the rest of us by sending the part out with a budget P965 motherboard model DP965LT which retails for about £70. The Extreme QX6700 press kit included the considerably more expensive D975XBX2, which sells for £150. The DP965LT doesn’t require any support for overclocking which makes things simple and cheap, and at the stock 2.66GHz our test results show that the QX6700 had very similar performance on both motherboards.
Satisfied that the DP965LT offered a decent platform we lowered the clock multiplier of the QX6700 to drop the clock speed to 2.4GHz, matching that of the Q6600. Both processors returned results that were essentially identical, so we are completely satisfied that the Q6600 is indeed a slightly slower QX6700 without the option of overclocking.
The 2.40GHz Q6600 has 90 per cent of the clock speed of the 2.67GHz Extreme QX6700 and in a pure test of processing power such as POV-Ray the performance differential is about ten per cent.
POV-Ray Benchmark Results
3DMark 06 Benchmark Results
In a more general test, like PCMark05, the picture is far less clear as the Q6600 lags behind the QX6700 by six per cent in the CPU element of the test which equates to five per cent overall. That probably puts too much emphasis on the performance of the CPU.
PCMark 05 Benchmark Results
Moving from a single-core processor to a dual-core is like the difference between night and day but advancing to a quad-core is only beneficial if you put a heavy load on your processor. In general use, we couldn’t tell a dual-core system from a quad-core but when the going gets tough the quad-core excels.
Fans of video rendering should form a line here, but whether you buy a Quad Q6600 or an Extreme QX6700 depends on the thickness of your wallet.
So now we have to turn to the price and value for money and this is where things get a bit vague.
At present Intel is unable or unwilling to tell us the price of the Q6600. However, we have a clue as Windows XP identifies the processor as a Xeon X3220 which will be the workstation version of the Q6600. Our roadmaps tell us that the 3220 will cost $851 - when sold in batches of 1,000 CPUs - which equates to a retail price of £549-599, so we expect the Q6600 to slip into Intel’s catalogue at £549-599 which prices it above every Core 2 Duo model. The Core 2 Extreme QX6700 remains at $999.
If our supposition is correct, the performance differential between the Q6600 and Extreme QX6700 is matched exactly by the price difference so you can’t call the Q6600 cheap, by any stretch of the imagination. Cheaper, perhaps, but not cheap.
Our roadmap also shows a Xeon 3210 running at 2.13GHz which will cost $690 so it doesn’t take much imagination to predict a Core 2 Quad Q6400 that costs £100 less than the Q6600 and retails at £449-499. That helps to fill out the range of quad-core desktop processors but we’re still talking about serious money.
But the roadmap's murky: the Q6400 isn't said to be shipping until later in the year, in Q3 2007, though a big price cut may come to the Q6600 in Q2, if industry mole claims are to be believed. Should the Q6600's price fall to $530, as has been suggested, it makes it a much more economical alternative to the Core 2 Extreme QX6700. Slower yes, but offering a better price:performance ratio.
Dual-core processors were a major step ahead of single-core CPUs, but the jury is still out on quad-cores. They’re likely to remain a niche interest until the price drops significantly and while the Q6600 is a step in the right direction it’s far too expensive for the mainstream. ®