Intel Core 2 Extreme QX9650

45nm of overclocking lovin'.

The Intel Core 2 Extreme QX9650 is based on the new 45nm Yorkfield core, and sports 50 percent more L2 cache than its predecessor. This ups the total to 12MB, and is shared equally between the two dies.

The cache and manufacturing changes mean better performance in cache-dependent benchmarks, and the chip also runs much cooler. How much cooler you ask? Well, we decided to do something a little unusual in the Atomic labs; we actually used the stock heatsink – shock horror!

Prepared for some nasty temperatures and with our fingers poised to flip the kill-switch on the PSU at the first sign of any kind of heat spike, we began an overclocking journey, and were surprised. Not only did we get a monstrous 4.3GHz overclock on the stock Intel cooler, but it was also running at decent temperatures in the mid to high 50s – impressive by anyone’s measure.

We were properly impressed by the speed of the QX9650 in the benchmarks. Our friend Super Pi 1M returned a blistering 9.5s flat when running at a mere 4.75GHz, a speed we hit with the aid of our single stage phase change cooler. The processor displayed similar performance to its 65nm brethren (Q6600, QX6700, QX6850 etc), however at a solid 450-500MHz less frequency on the core. This type of efficiency and impressive performance gain compared to a very similarly designed processor, such as the QX6850, is mainly thanks to the increase in L2 cache.

In benchmarks where the majority of the processing is done outside of the L2 cache, the performance is still strong, though nothing like the ridiculous gains found in cache-dependent applications. As mentioned, large gains were found in Super Pi 1M, but only few gains were found in Super Pi 32M.

Thanks to the die shrink and the use of high-K metal gates, the processor uses much less power than its forefathers. This is a contributing factor to the processor’s ability to run at relatively cool temperatures while overclocked. After all, it’s the increase in voltage that leads to the majority of the spiked increase in temperatures from overclocked chips. Running on a meagre 1.1v BIOS set vcore, the processor happily overclocked to a whopping 3.8GHz.

With Intel producing such massively overclockable chips, we are pants-wettingly excited by the thought this will bring even more people into the overclocking fold. We’re also looking forward to watching a renewed battle for national and world records as the new chips begin to hit the overclocking scene.

Because we tested well before the QX9650's official release, many motherboards -- even those from Gigabyte and Asus, the two largest companies in the game -- appear to have some difficulties fully recognising the CPU. Essentially, the big manufacturers have not had enough time to get their BIOSes in shape to keep up with this spry chip and its blistering speed. The CPU was stably hitting the high speeds we’ve raved about, but the motherboards couldn’t handle it. The max bootable FSB is considerably low and strap change holes are very apparent.

The best performing board with this processor at the time of testing was the Gigabyte GA-X38T-DQ6. It managed the highest FSB of the lot, at 400MHz bootable, and could still be raised to 475MHz from within Windows. This is a suspiciously high gain to achieve within Windows, and supports the strap change issues theory.