Build your own laptop

Posted at: Tuesday 1st August 2006 by James Morris

James Morris shows you how to custom-build your own performance laptop without spending a fortune

Processor options

Thanks to Intel's marketing dollars, the biggest brand in laptops by far is Centrino, so it's no surprise that most of the bare bones laptops available in the UK are aimed at this platform. It's worth noting, however, that there are two Pentium M sockets - Socket 478 and Socket 479. Since desktop Pentium M has started to take off, and most motherboards use Socket 479, processors using this form factor are much more readily available than the Socket 478 equivalents. A few vendors, such as www.savastore.com, stock the latter, but many only offer Socket 479 stock, so be careful when you're buying a processor for your laptop that you get the right version.

For sheer value, you can't beat the Celeron M, and the 1.5GHz model 340 is a bargain at £58.74 inc VAT (www.savastore.com). The Celeron M still uses basically the same Pentium M core, but with less Level 2 cache (512KB or 1MB vs 2MB). So it isn't like a 1.4GHz Celeron D - that really would be woeful. It's admittedly a slow processor compared with a Pentium M, but considering that Pentium III CPUs below 1GHz will run Windows XP and general office apps acceptably, it's more than enough for a budget laptop. The Thermal Design Power (TDP) is also still acceptable at 21W, so the Celeron M will provide decent battery life, although it doesn't support SpeedStep, so it won't clock down when idle to save power.

The Pentium M actually has an equal or higher TDP of 21-27W, depending on the model, but SpeedStep means that you'll get more life out of your battery. The 2MB of cache also significantly improves performance, and segments of this are turned off when not in use to preserve power. For the ultimate in battery-powered portability, the Pentium M is still the king, making it your best option if you're building a laptop to carry around all day. The most recent Dothan-core Pentium Ms sport a 533MHz FSB, so they can take more advantage of the bandwidth available from DDR2 memory. Conversely, only the 400-series Celeron Ms offer a 533MHz FSB.

Of course, the Pentium M has recently been usurped by the Core Duo processor. However, this requires Intel's 945 mobile chipset, which is fairly rare in bare bones laptops. Again, though, MSI has a couple of options - the MS-1034 and MS-1054 both offer Core Duo support, although at the time of writing, we had no information on availability or pricing.

Meanwhile, AMD-oriented laptops use Socket 754, the same socket used for AMD's desktop CPUs, so, in theory, you could use a cheap Sempron in your laptop or a Socket 754 Athlon 64. However, these CPUs have a TDP in excess of 60W, so you'll be limiting your battery life, and the laptop's cooling system may not be up to the job either. The same could be said of the Mobile Athlon 64. You're better off pairing a Socket 754 laptop with a Turion 64, although prices for this chip start at more than £100. AMD's Turions are available in two basic flavours - the ML and the MT. The ML is cheaper, but it has a 35W Thermal Design Power (TDP), so it consumes more power than the 25W TDP MT version. Both versions are available at a plethora of clock speeds, with 512KB or 1MB of Level 2 cache, depending on the model number.