Intel has given its Core 2 range a mid-life makeover, with new CPUs receiving a hike in clock speeds and bus frequencies. It’s likely to be the last refresh at the top end before the release of the new Penryn-microarchitecture parts towards the end of the year. Penryn-based processors will be the first produced with a 45nm fabrication process; the new CPUs remain on 65nm. In theory, they’ll work in 965- and 975-chipset motherboards, but there’s actually no benefit in doing this – the headline feature is higher FSB (front side bus) speeds, which will require the new P35 chipset to reap the rewards.
New Extreme Edition
The fastest new release is at the very top end of Intel’s enthusiast CPU line-up: the Core 2 Extreme Edition QX6850, replacing the QX6800 at the pinnacle of the food chain. A quad-core processor, it’s the third Core 2 Extreme model to be released since the original quad-core QX6700 at the end of last year (web ID: 100680). The new part’s basic specifications haven’t leapt massively, starting from 2.66GHz in the QX6700 and now hitting the 3GHz mark. The architecture remains identical, with two dual-core dies in one package, each with 4MB of L2 cache, making for a total of 8MB.
The major difference with the new release is its support for a 1,333MHz FSB frequency, up from a previous maximum of 1,066MHz. In theory, this represents a substantial 25% increase in bandwidth between the CPU and the rest of the system, which in particular should help memory performance with DDR3 RAM. Aside from its sheer speed, the QX6850 – like all other Extreme Edition Intel CPUs before it – is clock unlocked, allowing for direct clock-multiplier overclocking (standard Core 2 processors can be overclocked only indirectly by hiking FSB speeds).
As a general rule we’ve found you can overclock an Extreme Edition by one “speed bin” – our review sample ran perfectly happily with the clock multiplier increased from 9x to 10x, boosting it to 3.33GHz. And, in fact, a little more FSB tweaking got it up to 3.4GHz, running at 10x clock multiplier and 340MHz FSB (remembering that FSB speed is quad-pumped, giving an effective 1,360MHz), all with a stock cooler, giving us the fastest benchmark result ever of 2.04. At its standard clock, it still managed a mightily impressive result of 1.84.
New top-end dual core
Released at the same time as the QX6850 is a new standard Core 2 dual-core chip, the E6750. This is the new top-end standard part and comes in enormously cheaper than a QX6850 – not far from a sixth of the price, in fact. Even given the fact that you’re getting two fewer cores, it’s a hefty difference and betrays Intel’s determination to beat AMD on price when it comes to the volume end of the market. The new part runs with a 1,333MHz FSB, with a clock speed of 2.66GHz (the same as the existing E6700).
In comparison with the QX6850, the performance isn’t an open and shut case – with single-threaded code, the extra cores of the quad parts sometimes have little effect. With the majority of games, for instance, the E6750 will be within a whisker of the QX6850’s performance. In our application benchmarks, however, the overall difference is clear – a score of 1.43 for the E6750 against the QX6850’s 1.84 when fitted to the Gigabyte GA-P35T-DQ6 using 2GB of Kingston’s DDR3 HyperX RAM. But delving into the individual breakdowns shows that the gap closes with applications such as Office that aren’t extensively multithreaded; Office scores a figure of 1.42 against 1.53.
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