ATI Radeon HD 4850 X2

Last year, ATI released only one card with two GPUs on one board - the 3870 X2 - which was the fastest card we'd ever seen. This year, though, ATI has released two further dual-GPU cards, based on both the HD 4850 and HD 4870.

The HD 4850 X2 has two cores clocked at 650MHz - slightly higher than the single 625MHz clock of the standard HD 4850 - with the remaining spec in line with the reference card. A 64-bit OS is pretty much essential, because of the 2GB of onboard GDDR3 RAM.

While the HD 4850 X2 was almost twice as fast as the single card in our most demanding Crysis benchmark - managing 30fps to the HD 4850's 17fps - it was actually slower at low settings. Call of Duty 4 and Call of Juarez results were reassuringly stratospheric, though.

Unfortunately, Far Cry 2 proved problematic: the HD 4850 X2 scored 58fps in our high-quality test - seven frames slower than the equivalent single card - and was only slightly quicker in less demanding tests.

This can be explained by fickle driver support. The 8.11 Catalyst driver refused to recognise the card - we had to use a beta version instead. We're hopeful that the 8.12 update will fix these issues, but can't be certain until we've tried it ourselves.

If you're willing to persevere then the $550card could become a "budget" alternative to the HD 4870 X2 - it's already faster, in some tests, than anything Nvidia has to offer. At the moment, though, it's just too unpredictable to make it worth the huge investment.

• 
  Nvidia GeForce 9800 GX2
• 
  ATI Radeon HD 4650
• 
  ATI Radeon HD 4670
• 
  Nvidia GeForce 9600 GT, still almost on par with ATI's HD 4670
• 
  ATI Radeon HD 4870, why it's our new A-List graphics card
• - Recommended -
  ATI Radeon HD 4850, superb performance without the HD 4870's price tag
• 
  ATI Radeon HD 4830, can't match the 4870 but it's significantly cheaper
• 
  Nvidia GeForce 9800 GT, toe-to-toe with ATI's HD 4830
• 
  Nvidia GeForce 9800 GTX
• 
  Nvidia GeForce GTX 260+ (core 216)
• 
  Nvidia GeForce GTX 260
• 
  Nvidia GeForce 9800 GX2
• 
  Nvidia GeForce GTX 280
• 
  ATI Radeon HD 4870 X2
• 
  Nvidia GeForce GTX 295
• 
  Nvidia GeForce GTX 285
• 
  Nvidia GeForce 9600 GSO
• 
  Nvidia GeForce 9500 GT
• 
  ATI Radeon 4550
• 
  Nvidia GeForce 9400 GT
• - Best Value -
  ATI Radeon HD 4350, best value graphics card at budget prices