Battery life is not exactly a prime concern for a laptop weighing in at over seven kilos with its power brick included - even Rock itself calls the Xtreme 840 SLI range "mobile-ish". Nevertheless, with some conservative settings you can expect to get just about an hour's worth of GPU-intensive play out of this gaming monster before you'll need to head for the nearest wall-socket, though SLI is deactivated on battery.
So finally we have a relatively quiet 'gaming laptop' that can run most modern games the way they were meant to be played with a screen that will actually let you appreciate it, but you do pay for the privilege. When you think of the kind of desktop gaming monster £3,000 can buy you, the comparison is simply depressing. For example, you could get the fully kitted out water-cooled and overclocked Wired2Fire HellSpawn ALC Core i7 PC (£1,263) with the top-end 24in HP LP2475w (£410) and still have £1,327 left over to get some amazing speakers and peripherals.
If you do insist on a desktop replacement, then for what you get Rock's Xtreme 840SLI-X9100 isn't bad value. Though Novatech offers essentially the same chassis with a similar setup, thanks to its three-year warranty - which is included as standard - Rock is the better-value option.
In fact, considering how much more important graphics cards are than CPUs when it comes to real-world gaming performance, we'd recommend going for a configuration like Rock's X840SLI-P8700. It might only offer half the hard drive space of our test machine, but the Core 2 Duo 2.53GHz processor with the same 280M GTX SLI graphics setup should still give you similarly good gaming performance while saving almost £600.
Here again it's definitely worth checking out other manufacturers to compare though, since aside from the great screen there's plenty to fault about the Xtreme 840 SLI's chassis - albeit little that can't be fixed. You can get around the malfunctioning spacebar, for example, by using external peripherals such as Logitech's G13 Gameboard, but when you're spending this kind of money you shouldn't have to.
It's big in every way, but despite its excellent Full HD screen, some innovative features and stonking performance in games, there are enough niggles to hold Rock's Xtreme 840SLI-X9100 back from coming recommended.