MSI Radeon HD 2900 XT Crossfire
Crossfire Performance in Windows XP
Adding a second graphics card boosts the frame rate in Battlefield 2142 by between 11 and 62 percent. Higher resolutions benefit the most from the second card. The maximum performance boost in Doom 3 is 35percent and only manifests itself in high resolutions with anti-aliasing enabled. At 1024 x 768 with all filters disabled, the dual-card setup actually runs slower than a single-card system. Oblivion greatly benefits from the second card, almost doubling its performance. The added performance ranges from 55 to 84 percent. Even in the 1920 resolution, the game still skims along at a brisk 40.5 fps (single card – 22 fps).
Prey behaves just like Doom3, with the second card actually slowing the game down at 1024 with filters disabled. At higher resolutions, Crossfire yields between 22 and 72 percent more performance. The cumulative performance delta between the single Radeon HD 2900 XT (1809.6 fps) and the Crossfire configuration (2197.1 fps) amounts to 387.5 fps, or 21.4 percent.
Crossfire Performance in Windows Vista
The catalyst 7.9 driver still seems to offer rather poor support for Crossfire configurations under Vista. Neither Bioshock, nor Company of Heroes, nor World in Conflict display a performance gain. On the contrary, the tandem configuration actually ran slower than the single-card setup. Lost Planet can benefit from the second card’s rendering power with FSAA enabled, gaining between 65 % and 79 % more performance. As before, we can see the same pattern – the higher the resolution, the higher the performance advantage over a single card.
Both the noise and the temperature increase in a Crossfire configuration. While a single Radeon HD 2900 XT remains very quiet in 2D mode, the fans spin up briefly every now and then with two cards running in tandem. Where a single card’s heat output ranges between 62°C and 82°C, the dual card setup produces 10°C more. Unsurprisingly, the noise level is also higher in 3D mode, measuring up to 54 db(A) for the Crossfire setup, compared to a single card’s 51.4 db(A).
Each of our review samples came with a flexible Crossfire bridge. Two such bridges are required so that the two cards can detect each other and combine their rendering power. If you plan to build a Crossfire system, check with your store to ensure that your cards come with all of the required equipment, including these connectors.
First ! e vai!
"The HIS card only comes with DVI connectors, which makes dual-link a sensible choice for the 1920 resolution."
Uh. No, it really doesn't.
The HDMI(1.2 and below) type A connector is equivalent to
a single-link DVI-D connector; the adaptor is purely
mechanical. Dual-link DVI is equivalent to the HDMI type
B connector, which is largely unused (although I have
hopes, because HDMI 1.3 type B can do 680MPix/s).
1920x1080p/60 fits quite nicely through the bandwidth
limit (165MHz) of an HDMI 1.2 type A connector, and
equally well through a single-link DVI connector -
as you can tell by the multitude of single-link DVI
24" 1920x1200@60Hz monitors on the market.
Dual-link DVI would give you 48bpp colour support at
1920x1080, but that's irrelevant if only a single link
is being used, via an HDMI adaptor. Also, the DVI
connector is perfectly capable of transmitting the
audio component of HDMI (the audio component uses the
same signal wires as the video), if it can be routed
to the card. Whether the content permits the audio to
be routed without HDCP is beyond my expertise.
Also, at the risk of testing my mathematical abilities:
"In Windows XP, the performance delta between the two cards in cumulative frame rate is now less than 20fps (Geforce 8800GTS 1878.9 fps, Radeon HD 2900 XT 1809.6 fps)."
That sounds like "less than 70fps" to me (not that it
makes much difference, obviously - they *are* close.)