Our Best Buy Intel Sandy Bridge processor, the Core i5-2500K, is ripe for overclocking. It has an unlocked processor multiplier, which means you can make the processor run faster than its stock speed without changing the speed of other components such as the memory, so making it easier to achieve a stable overclock.
Processor multiplier control was available on Intel's P67 Express chipset, but not on H67 Express boards - which supported the Sandy Bridge processors' integrated graphics. This meant that, when buying a motherboard, you had to choose between overclocking and on-board graphics.
The Z68 Express chipset finally brings these two features together, providing both multiplier-based overclocking and outputs for the processor's onboard graphics. Being able to use the onboard graphics also gives you access to Intel's Quick Sync technology, which speeds up video encoding in certain applications. Z68 Express also has support for SSD caching, which uses a small-capacity SSD to store frequently-accessed data to speed up Windows.
Sapphire's Z68 Pure Platinum is a fairly inexpensive Z68 Express board. It's fully loaded, though; you get VGA, DVI, HDMI and DisplayPort sockets on the rear for the processor's graphics, built-in Bluetooth, USB3 and 7.1 sound outputs (but no optical or coaxial S/PDIF, though you can still output digital audio over HDMI). On the board itself are three PCI Express x16 slots and two PCI expansion ports, four SATA3 and four SATA2 sockets and four USB2 headers for a further eight USB2 ports, if your case has the necessary ports. There are no USB3 headers for extra USB3 ports, unfortunately.
The board has a standard text BIOS rather than a graphical UEFI, so it took us a while to find the overclocking options. There are no overclocking presets, but you can adjust the processor ratio and motherboard bus speed easily enough.
Quick Sync only supports certain applications, so wouldn't speed up our Handbrake-based video encoding benchmark. When testing with Cyberlink's MediaEspresso, the time taken to encode a six-minute 1080p AVCHD video to iPhone 4 format dropped from 2m 56s with Quick Sync disabled to 1m 58s with it turned on - a 33% faster encode.
Quick Sync is well worth using, but fitting a dedicated graphics card, as most of those interested in overclocking are likely to do, will disable the Sandy Bridge processor's onboard graphics and therefore Quick Sync will no longer work. To get around this Sapphire provides a program called Virtu, which lets you keep the onboard graphics active while still using the discrete graphics card. Virtu worked fine for us in combination with an AMD Radeon HD 5770 - Quick Sync ran at full speed and so did our graphics benchmarks.
The Z68 Express chipset's other big feature is SSD caching. Having an SSD as your Windows boot disk makes sense, as you can take advantage of an SSD's fast speeds to increase loading times for your operating system and programs, while leaving all your documents and media files on a normal, larger hard disk. The disadvantage of this arrangement is that SSDs are expensive and have a relatively small capacity; given that modern games can be over 8GB each, you'll quickly fill up a £70 64GB disk.