Moving on, the Sapphire 4850 X2 has a core speed of 625MHz with an effective memory speed of 1986MHz. It zipped through all the tests and compared very favourably with the GTX 280 in 3DMark and less well in Far Cry 2. We had the quality settings in Far Cry 2 set to Very High, which is a stern test but the 4850 X2 pulled through. The power draw was higher than GTX 280 in Windows at 165W but under load the figure was the same.
Power Draw Results
Power draw in Watts
Nb. the two 4870 X2 scores use, respectively, the Catalyst 8.551.1.71310 and 8.11 drivers
We used the Catalyst 8.551.1.71310 driver to overclock the Sapphire to a core speed of 680MHz and memory speed of 2370MHz. This raised performance by ten per cent in 3DMark and Far Cry on DirectX 9 although this advantage dropped to a mere one frame per second in Far Cry 2 when we used DirectX 10.
The 4870 X2 uses the same technology as the 4850 X2 except that the core speed is higher - 750MHz - and the effective memory speed is a colossal 3600MHz due to the nature of GDDR 5 memory. This extra speed delivered 20-30 percent more performance in 3DMark compared to 4850 X2, and in Far Cry 2 the 4870 X2 delivered a few extra frames per second over 4850 X2. The power draw of the 4870 X2 is scarily high: 210W in Windows and 350W under load.
Just for larks, we hooked up the 4850 X2 and 4870 X2 in CrossFireX which cranked up 3DMark performance by a small amount. However, it clobbered performance in Far Cry 2, which pretty much sums up our experiences with CrossFire over the years.
The Sapphire HD 4850 X2 was horribly noisy because the drivers were only controlling one fan while the other fan roared away at full speed. Sapphire tells us that it will be releasing an updated Bios that will fix the noise issue in conjunction with a revised driver.
The Sapphire HD 4850 X2 delivers the same performance as a single GTX 280 but unfortunately the horrendous dollar exchange rate means that they also cost the same. And that makes the Sapphire look far too complicated when it is compared to the Nvidia alternative.
Sapphire Radeon HD 4850 X2 dual-GPU graphics card
The two 4870 X2 bars in the charts have the same description, I assume the second is overclocked? However some of the benchmark/timing results for various cards are clearly spurious compared to their overall performance differentials. I suggest you revisit this.
ATI Linux driver support has improved dramatically from several years ago. I have a number of machines with ATI cards (3870, 24-something, a 690 based uATX board with integrated graphics and a Dell with embedded ATI graphics). The ATI installer is pretty bulletproof and the performance is good. Not at all like back in the days of the 9700. I used to worry about using ATI with Linux: I do not anymore.
I have read that neither ATI nor Nvidia supports CF/SLI under Linux. I don't know if it is true. Can anyone confirm or refute?
The driver is built around a kernel module and if the kernel is updated then the graphics driver must be reinstalled, which is a pain. But Nvidia is the same in this regard.
FWIW, ATI's CAL or Stream Computing SDK also runs on Linux now. As much as I have played with it, it seems to work well (I have not had as much experience with CAL as with CUDA though.)
AFAIK - as of about 8 months ago - neither CAL nor CUDA will use both GPUs if the GPUs are in Crossfire/SLI mode. This would be a problem with ATI or Nvidia. If the cards are not paired up then both are available - I've verified this with an Nvidia 8600 and 8800 in the same box, and it is what ATI says in it's docs.
Looks as if
ATI may finally be getting their act together. When I got to rebuild (my now three year old) game rig I may have to take a look at their cards in comparison to nVidia, thanks.
165W in Windows?
Quick Linux compatibility check?
Given that you've probably got quite a few Linux users in your readership, would it be possible to do a brief check of hardware like this on Linux?
Nvidia kit generally has very good OpenGL support, and is very good with simulators like X-Plane, Silent Wings or FlightGear. It would be nice if you could see if the ATI/AMD kit is beginning to improve the Linux driver support since the two companies merged.
It would be nice if you could do a more in-depth report than "yes, it works and it looks nice", but even thats better than nothing :-)