The life and times of the modern motherboard

Posted at: Tuesday 27th November 2007 by Alex Watson

Ever wondered how a motherboard and its BIOS are designed and made? What makes one a brilliant overclocker and another as stable as a plate of jelly on a bouncy castle? Alex Watson investigates.

Plenty of ideas do work, however, and there are big advantages to allotting time for tinkering and experimentation. 'Engineers are essentially getting started before products are even started,' says Yu. 'We constantly have experimental boards on the side, so when an innovation is ready, I can take it and plug it into my current project.' It's also more efficient, since features can be shared between products. At the demo, he shows a board running a new power management feature called EPU. Originally developed for its mainstream boards, it's now also being added to high-end products. 'We think energy efficiency is the right thing to do, so we took it from the mainstream boards and put it on the ROG boards.'

A question of performance

As well as integrating the latest features and innovations, other choices need to be made regarding the design of a board and its BIOS. In the labs, some motherboards, despite using the same chipset, perform and overclock differently. 'Motherboards [based on the same chipset] can present different characteristics and performance scores,' says Yu.

'Some might have a design that favours overclocking while others favour performance results, as there's a trade-off between the two. It's like finding the balance between making a drag racing-style car, with straight-line speed, or making a sports car that can get a good lap time on a curved circuit. Choices regarding layout, traces and parts could contribute to the performance difference between motherboards with the same chipset.' According to Asus' George Chen, a good motherboard should have 'a high tolerance of voltage increases, so it will need strong signal driving and yet sensitive receiving ability. It should also have a good PLL to stabilise it at higher clock frequencies, and low power consumption to prevent overheating when the voltage is raised. It should also have undergone serious testing when it was made.'

However, the engineers with whom we spoke agree that the combination of a motherboard's hardware and its BIOS contributes to its performance and overclockability. As Thomas Chang from Gigabyte puts it, 'The hardware provides the base line for overclocking, but it's only by writing a BIOS with good overclocking methods - when to overclock, and tweaking CPU and chipset registers - that users will be able to enjoy extra performance when they overclock the CPU and memory.'

Foxconn's Holst Cheng pointed out that while it's simple for a BIOS to control one function - changing the FSB, for instance - it becomes a lot more complex when changing multiple settings. 'It gets to be complex when you're controlling three or more functions,' he explained. 'Correlating them correctly is very tricky.'

The starting point to writing a high-performance BIOS with excellent overclocking abilities is investigating the motherboard's chosen chipset. When a new chipset is introduced, such as Intel's recently launched X38, it's an unknown quantity - X38, for instance, has a totally different BIOS code base even to P35 - so it's a race between motherboard manufacturers to find out as much as they can about how it works. 'Intel is very fair to each motherboard manufacturer. It provides a set of reference designs for its customers. On the hardware side, this means that Intel provides information such as its spec, a data sheet and a reference circuit. For software reference, Intel provides drivers and a reference BIOS code, along with optional ROMs for special devices such as RAID and LAN,' explains Asus' George Chen.