Labs

Graphics cards: Entry-level

As always, we use real-world games to test graphics cards rather than synthetic benchmarks, as real games provide more meaningful results that are simple to interpret. We've chosen two titles that accurately tell us how a card will handle both DirectX and OpenGL games, and we run a range of timedemo tests for each.

Despite being reasonably old, Far Cry is still a tough test today thanks to the latest patch, which adds demanding HDR (high dynamic range) lighting effects. These provide far greater contrast ratios than before, allowing for extremes of light and dark along with superior vibrancy and detail. The impact is nothing short of spectacular and, once you've experienced HDR in action, you won't want to switch it off.

We've chosen Call of Duty 2 because it really pushes cards to their limits. As well as being a good test of OpenGL optimisation, it's extremely texture intensive but also very scalable in its video options.

Every card on test is capable of running recent games if you're willing to drop to 800 x 600 and lower the detail settings. But while some gamers will be happy with this level of detail, others will want to experience the latest games in their full high-resolution glory. This is why our toughest tests have all the detail options set to Very High with HDR enabled in Far Cry, and the maximum possible quality in Call of Duty 2.

The entry-level cards, however, are tested at 1,024 x 768 with AA (anti-aliasing) and AF (anisotropic filtering) disabled, and with Textures set to Normal in Call of Duty 2. For the mid-range cards (£80-£180), we run these 1,024 x 768 tests in addition to a second set at 1,280 x 1,024. In Far Cry, we still leave AA and AF switched off, but Call of Duty 2 is run with 4x AA and 8x AF as well as High Textures.

Finally, the cards costing more than £180 are put through their paces at 1,600 x 1,200 in addition to the 1,280 x 1,024 tests. In Call of Duty 2, we select Extra Textures, 4x AA and 8x AF, and in Far Cry we opt for 8x AF. Currently, Nvidia cards can't simultaneously perform HDR rendering and AA, so to retain a level playing field between ATi and Nvidia cards we leave AA turned off. Only the most powerful cards will emerge from this assault course with playable frame rates.

In order that we find each card's maximum performance, we build a test rig that eliminates all other bottlenecks from the system. To this end, we use an Asus A8N32-SLI Deluxe motherboard, which uses the Nforce4 dual-X16 SLI chipset. We fit a 2.6GHz AMD Athlon FX-60 processor and 1GB of Crucial PC3200 RAM, split over two memory sticks. To ensure the hard disk doesn't slow things down, we use a 36GB, 10,000rpm Western Digital Raptor.

How we work out the ratings

At the bottom of each review, you'll see four star ratings: one for Performance, one for Features, another for Value for Money and a final Overall score.

The Performance score is calculated by summing the average frame rates achieved by each card in both games. The result is then converted into a score out of six, which is comparable across the whole group.

For the Features score, we carefully allocate points to each package. We reward the array of outputs and inputs, as well as any supplied cables and applications. Passive heatsinks or quiet fans are also noted, as are games bundles.

The Value for Money rating is based on a weighted average of the Performance and Features & Design scores. The weightings depend on the category: features are weighted higher for entry-level cards, and performance for high-end models. We then factor in exactly how much each card costs (including delivery) to give a bang-per-buck result.

The Overall score is simply a straight average of the other three scores. Rather than giving a Labs Winner award this month, we give a Recommended award to the best card in each price category.

Performance analysis

The results from a month's worth of intensive testing are in, and there are some notable trends. At the very top end, ATi's X1900 series cards are the fastest, but Nvidia's 7900 GTX just about keeps up with the X1900 XT all the way. Interestingly, we saw different results in the two games we tested, but ATi cards handle the texture-intensive Call of Duty 2 better than Nvidia cards.

You'll notice that in Far Cry at 1,600 x 1,200, the top three cards have a clear lead over the rest, with 11fps separating the 7900 GTX from the X1800 XT. But glance at the same Call of Duty 2 test and the X1800 XT has jumped ahead of the GTX. It's significant that the four cards ahead of the rest in this game are those with 512MB of RAM, suggesting that the 'Extra' quality textures setting really benefits from this amount of memory.

Looking at the mid-range, ATi's X1800 GTO jumps up above the 7600 GT and the 7800 GT in Call of Duty 2, reinforcing the notion that ATi handles it better. And out of the entry-level cards, the two ATi Radeon Pro cards jump to the top in Call of Duty 2.

Before you buy

In an ideal world, we'd all buy the card at the top of the speed charts and run around the jungles of Far Cry in glorious HDR lighting at 1,600 x 1,200, but things aren't that simple. Not only will your budget come into play, but there are several factors that you also need to consider before making your choice.

We tested all of these cards on a 23in TFT monitor, capable of 1,600 x 1,200, but if you have a TFT smaller than 20in you won't be able run games beyond 1,280 x 1,024. You may get away with running a 17in CRT at 1,600 x 1,200, but there's simply no reason to buy any of the £180+ cards unless your monitor can comfortably support this resolution. Otherwise, the power will be wasted until you upgrade your monitor or the next generation of more demanding games appear.

Additionally, you should 'match' a graphics card to your current system, particularly the CPU. The CPU can be a significant bottleneck, so there's no point pairing a Radeon X1900 XTX with a 1.8GHz AMD Sempron 3100+: you'll limit the card's performance. We ran some tests and found that a 1.8GHz Sempron 3100+ can just about handle the mid-range cards without limiting frame rates. But for the high-end cards, you'll need a decent system to back them up: we'd suggest you choose a dual-core processor or at least an Athlon 64 4000+ or Intel equivalent.

As value will be the overriding factor for most people, there are several cards to point out. The mid-range is where you'll find the best value. The GeForce 7600 GT offers the best bang-per-buck, with the Radeon X1800 GTO being a decent alternative. At the entry level, the 7600 GS offers gaming at reasonable resolutions as well as silent-running for just £71, and the X1300 Pro offers decent features for £62. You won't find great value at the top end, but the 7900 GT is relatively affordable at under £200 yet allows you to use advanced quality effects and high resolutions.