Rock's 7900 GTX-equipped Xtreme CTX Pro is probably the perfect mobile for gamers who don't really want to be all that mobile. Ignoring its vast weight and unwieldy dimensions, the 7900GTX, bolstered by 512MB of GDDR3, pumps the CTX Pro's graphics along superbly.

You see, the 7900 GTX is a gamers' card through and through, and being matched with the CTX Pro's Core 2 Duo and 1GB RAM means some exceptionally quick frame rates and silky smooth gaming playback. Yet that was the CTX Pro in leisure mode. What we have here is the CTX Pro wired for a heavy day's labour.

This version of the CTX Pro sees Rock dispense with Nvidia's 7900GTX in favour of its Quadro FX 2500M - a professional level graphics card that, while still based on the same GPU as the 7900GTX, is geared more towards 3D rendering and graphic applications. Nvidia manages this through its performance driver support, upping the 3D capabilities of the card at the cost of gaming performance.

In terms of architecture, the Quadro FX 2500M is still a 24 pixel-pipeline, 8 vertex-pipeline chip capable of producing 181m vertices per second and filling 10.8bn polygons in the same timeframe. It's still a 500MHz processor, still carries 512MB of onboard RAM, which still fires at 600MHz. That's about the same throughput and outright power of Nvidia's entry-level and midrange desktop cards. In fact, when you take into consideration that the FX 2500M draws 100W of power and that it's capable of HDTV support, its raw specs don't look that far off Nvidia's Quadro FX 4500.

So what performance difference can we expect from the FX 2500M? Let's remember that, superficially at least, this is the same machine as the 7900 model, just with a different graphics engine: a Core 2 Duo T7600 running at 2.33GHz is backed by 2GB of fast 667MHz DDR2 RAM and a 100GB hard drive running at 72,000rpm.

No apologies

Previously we commented on the solidity of such a selection, with Rock making no apologies for its lurch towards an all-out powerhouse of a laptop. And indeed that's precisely what the CTX Pro was and still is - only this time it's aimed at graphics pros rather than gamers.

Compared with the GeForce 7900 GTX, this rendition of the CTX Pro clocked a 3D Mark 06 score of 5,861 - which may seem a tad disappointing. But the Quadro FX 2500M isn't made for gaming, it's made for doing, and while its frames per second is high enough and its rendering is smooth and glitch-free, it's in the professional tasks you ask of it that its quality really shines.

Take Photoshop. The graphics engine on the Quadro FX 2500M took well over a minute less than the 7900GTX to rip through a huge batch conversion script. And we know that the RAM, processor speed and processor itself are identical to the 7900 version. So if you want to know whether the card's worth the extra £250 outlay, you have your answer.

Similar results are witnessed when running some of the Photoshop CS3 beta's 3D tools. A Core 2 Duo Apple MacBook Pro benchmarked a complex render at 2 mins 20 sec, while the CTX here managed it in just over a minute.

The downside of the Quadro FX architecture is that it consumes about as much power as the rest of the CTX's components put together. Its 100W consumption kills battery life. While the 7900GTX-equipped CTX Pro pulled in a disappointing one hour and 22 minutes before choking, the extra zap needed to power the Quadro almost halves this again.

In the end, we managed to record a battery life from full charge to death lasting just under an hour, in spite of Nvidia's built-in PowerMizer power management technology, which claims to balance a decent battery life with its graphic output.

Rock wants graphics pros to sit up and pay attention to the Xtreme CTX Pro, and it's the CTX's power - and not its stamina - that will set tongues wagging. Indeed, Rock is most probably banking on the fact that most designers and graphics pros will want a laptop with portability in mind, rather than as a de facto design feature, and with the CTX Pro this is exactly what it's produced.

It may be big, heavy, to some ugly and have gluttonous power consumption, but if it's pure graphical computing power you need, the CTX Pro and its Quadro FX 2500M has it in spades. Tom Dennis