The Intel D975XBX2 is an incremental upgrade to the D975XBX. It's based on the tried and trusted 975X chipset, but will support Intel's new quad-core processor.

Being specifically designed for use with quad-core architecture it provides a wide range of voltage options and optimisations, and comes with two PCI Express slots that offer either one x16 lane or two x8 lanes.

Up to 8GB of DDR2 667/533 Ram is supported. Intel notes in its documentation that although DDR2 800 works, it is not officially supported on the D975XBX2. The board also features Raid, 7.1 surround sound, and Gigabit Lan.

Initially, we couldn't overclock the quad-core processor beyond 3GHz using this motherboard. We had the same problem with the Hi-Grade Ultis Tachyon PC system and it was only after we upgraded the Bios that we finally started to get much higher overclocks.

When we overclocked the CPU too far Windows XP refused boot and only a Bios factory reset would spring it back into life. With the D975XBX2 you have to use the Bios Configuration Setup Jumper, however this didn't always work smoothly and we had difficultly getting into the Bios reliably. We'd prefer a simple reset jumper like some other motherboards.

An Intel reference heat sink and fan was used during the testing and it didn't have any automatic fan speed control. The result was the loudest we have ever heard - it was completely unbearable and meant we turned off the machine whenever we could.

Intel documentation says retail kits should ship with a fully functional fan control system that's based on how hot the CPU is; we're expecting to soon get hold of a Bios update to resolve the problem on our test rig. Hi-Grade got round this problem with its quad-core system by using a third-party cooling solution.

The processor input voltage settings are a vast improvement on Intel motherboards of old. There is a surprisingly large array of settings and the CPU core voltage adjustments are far more granulated compared to previous boards.

Ram voltage and CAS (Column Address Strobe) timing options can be changed but the settings are still not as comprehensive as motherboards from Asus or Gigabyte, which offer more specific fine-tuning such as half clock-cycle CAS timings (3.5 etc.).

The D975XBX2 will be similarly priced to its predecessor at around £180. This is extremely expensive when compared with the competition from the likes of Abit and DFI so we'd recommend shopping around if you're looking to build your own quad-core system.