Rock Xtreme SL Pro

Verdict: You'll need a big lap for this laptop - it has a 20in screen, geforce go 7950 gtx sli graphics and two hard disks in raid

You don't usually associate laptops with excess, but the Rock Xtreme SL Pro is positively Bacchanalian in its abandon. It has two 100GB mobile hard disks in RAID 0, two GeForce Go 7950 GTX graphics cards in SLI, a 20in widescreen TFT display and a 2GHz dual-core AMD Turion 64 X2 TL-60 CPU.

Weighing in at 6.9kg, not only is this laptop the largest we've seen, but it's also the heaviest, especially if you add in the 1.1kg external power brick. The Xtreme SL Pro is so massive that it even has a huge, specially designed, boxy rucksack in which to carry it around. This shouldn't count against the SL Pro, of course, as Rock isn't exactly claiming that it's in the 'thin and light' category. The Xtreme SL Pro is perhaps the first laptop to truly merit the label 'desktop replacement' - as we found out, you can't practically use the system anywhere apart from a large, solid table.

To some people, this will seem silly; after all, why not just buy a desktop system if you're going to keep it on your desk? Even with its impressive bulk, it's much quicker and simpler to move the SL Pro from desk to desk than it is to lug a complete desktop system to a new home. It might be massive, but it's recognisably a laptop, complete with standard clamshell-style chassis, so there's no need to take special precautions to avoid scratching the SL Pro's monitor while you're in transit to a LAN party, or to pack up any extra peripherals and cables apart from the power brick.

The reason for the SL Pro's prodigious dimensions is its crowning glory, a 20in widescreen TFT display. The crisp, bright panel has a native resolution of 1,680 x 1,050, so it has the same pixel density, and is just as expansive, as an equivalent 20in desktop model, like those we reviewed in our recent Labs test. Thankfully, though, the screen attached to the SL Pro is lighter and thinner than a desktop panel. It sports a glossy, reflective coating, designed to enhance the panel's colour depth and contrast levels. Text was sharp and easy to read, and for games and films, the screen offers a more engaging image than a traditional matt-finish monitor - provided, of course, you shield it from any distracting reflections. DVDs and 720p HD film trailers looked great, although the panel doesn't have the requisite resolution to handle full-on 1080p HD content.

We've seen laptops with single GeForce Go 7950 GTXs, such as the Evesham Voyager C720DC Plus, and, as we reported then, it's just a GeForce Go 7900 GTX with a bit of nitro. In becoming the Go 7950 GTX, the GPU has gained 75MHz and now runs at 575MHz, and the 512MB of GDDR3 is 100MHz faster at 700MHz (1.4GHz effective). It still has 24 pixel shaders with 8 vertex pipes, the same number as that of desktop 7950 GPUs, so there's no shortage of graphics power; with two such cards, the SL Pro is ... well, 'tall of graphics power' isn't a saying, but you get the idea.

We're unforgiving with laptop manufacturers that don't fit machines with screens with a resolution that suits their graphics powers, which is the reason that the Evesham isn't on the Elite list, as you can't currently buy it with a 1,680 x 1,050 screen and a GeForce Go 7950 GTX. However, the SL Pro is one of the few laptops on the market that could probably handle playing games at 1,920 x 1,200. That said, its 1,680 x 1,050 screen will prolong the lifespan of its dual DirectX 9 cards.

Even though it has a full numeric keypad in addition to the rest of the keys, the SL Pro's keyboard - and your hands - look tiny in comparison with the rest of it. There are two round stereo speakers and a sub built into the SL Pro's considerable base, although, not surprisingly, this audio setup can safely and sadly be declared almost bass-free. As it's based on the nForce4 chipset, you're stuck with 6-channel AC97 audio rather than 8-channel HD Audio, but there's a mini-jack S/PDIF port in addition to the usual analogue jacks. Unfortunately, unless you're watching a Hollywood action fest at a deafening volume, you'll hear the SL Pro's annoying fans throughout the majority of the film. Even when idle, it clearly needs a fair amount of cooling, and the grating metallic fan noise is made even more distracting by the fact that it frequently changes in pitch or stops altogether.

The SL Pro is available with up to 2.8GB of DDR2 (actually 3GB, but some is lost due to a chipset limitation), and we would really recommend getting 2GB of DDR2, since our review sample had 1GB and suffered as a result in games. There are plenty of I/O options: five USB 2 ports in total, with three on the right and two around the back. This is a smart move for a machine that's targeting gaming enthusiasts, who might be reasonably be expected to hook up a gaming mouse, a couple of thumb drives and other gadgets, such as MP3 players. Also at the back of the machine is a DVI output for connecting an external monitor, an S-Video output, FireWire, and even a serial port if you're in need of some old-school connectivity. There's a 56k modem built in, along with Gigabit LAN, and 802.11b/g wireless LAN. The optical drive is an 8x DVD writer.

PERFORMANCE

On paper, the weakest link in the SL Pro's spec is its CPU. Intel's mobile processors carried the company when it was trying to inflict NetBurst Pentium 4 CPUs on desktop users, and its new Core 2 chips draw heavily on the lessons of the Pentium M. AMD's laptop CPUs have struggled to keep up, although its dual-core Turion 64 X2s are far from dreadful, and can keep pace, clock for clock, with Core Duos. Core 2 Duos make them look second-best, though, so you can't help but feel that such a relatively inefficient, timidly clocked 2GHz CPU looks out of place in such a premium system as the SL Pro.

Our apprehension was confirmed when the SL Pro proved to be a poor performer in 2D applications. Paint Shop Pro isn't multithreaded, so it doesn't get much benefit from the Turion's two cores. The SL Pro's lowly score of 1.06 is pretty ropey - the Evesham, with its top-of-the-range 2.33GHz Core 2 Duo T7600, scored 1.36. The Rock is equally at sea in the DVD encoding test, scoring 1.02 compared to the Evesham's 1.33. In short, regardless of form factor, an overall score of 1.15 from a £2,500 computer is pretty poor. Of course, it isn't really Rock's fault; to run SLI you need an Nvidia SLI chipset, which isn't compatible (yet) with mobile Intel Core 2 Duos.

With two GeForce Go 7950 GTX graphics cards in SLI, gaming was an entirely different matter. Need for Speed: Most Wanted and Prey were silky-smooth at 1,680 x 1,050 with 2x AA and 8x AF, and we were able to increase the AA and AF beyond those levels in both games for an even smoother image. As most modern games rely much more on the GPU rather than the CPU, the SL Pro goes some way to redeeming itself in this department. We gave Company of Heroes a spin; this game, with its plentiful units, does rely on the CPU somewhat. The game proved to be a harder task, and the SL Pro's frame rates dropped to 14fps at times. Company of Heroes is a strategy game, though, so a high frame rate isn't as crucial as it is in an FPS or driving game. Oblivion was similarly punishing for the SL Pro, and at 1,680 x 1,050, we had trouble outdoors, even when we dropped the detail levels to default (albeit with HDR); again, the frame rate dipped into the high teens.

For an SLI system, F.E.A.R. is always fun, and at 1,680 x 1,050, the frame rate never dropped below 35fps. However, when we played through an entire level, it was evident on some of the larger maps that the game was demanding more RAM than our SL Pro had to offer. In some sections, there was visible stuttering as the game was forced to use the laptop's hard disk as virtual memory. For modern games, 2GB of memory is becoming mandatory and, with only 1GB in memory-hogging games such as F.E.A.R. and Battlefield 2, you can't make full use of the graphics power provided by the two mobile 7950 GTX GeForce GPUs.

You can, of course, argue about SLI itself. To regular readers, the following caveats will be as familiar as childhood fairy tales. SLI's success depends on driver support, and drivers for GeForce Go are updated less frequently than they are for desktop cards. You also need games to play ball with the SLI, so while the SL Pro averaged 82fps in F.E.A.R. compared to 59fps for the Evesham and its single Go 7950 GTX, in NFS: Most Wanted, the SL Pro was slightly slower than the Evesham, with SLI unable to make up for its tardy CPU.

CONCLUSION

With the right game, the SL Pro is a formidable machine. The large widescreen monitor combined with a decent set of audio ports also equates to an impressive mobile home cinema system, which is an attractive bonus. Unfortunately, overall, the SL Pro is a mixed bag. The only mobile motherboard chipset at the moment that supports SLI is the nForce4 SLI chipset, which doesn't support Core 2 Duos. With a Turion 64 X2 in the driving seat, the SL Pro is poor value for money in terms of 2D performance. In SLI-optimised games, however, it's awesome, leaving it stuck halfway between being a fearsome top-end gaming machine and a budget-conscious compromise. If your heart is set on a larger-than-life gaming laptop, you wait until a mobile chipset is released that supports both Core 2 Duo and SLI. Add to this hypothetical package 2GB of RAM and a 1,920 x 1,200 TFT, and you'd really be talking.

• Antec Mini P180 - Cases
• Turok - Games
• ATI Radeon HD 4870 X2 - Graphics cards
• Cooler Master Cosmos S - Cases
• Lian Li PC-P60 Armorsuit - Cases
• Asus Rampage Formula - Motherboards
• Gigabyte GV-NX96T512H-B - Graphics cards