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- Date:
- Wednesday, March 05, 2008
- Author:
- Brent Justice
- Editor:
- Kyle Bennett
- Google +1
ATI Radeon HD 3870 X2 CrossFireX
The power of 4 GPUs is now possible with AMD’s ATI CrossFireX technology. We evaluate two Radeon HD 3870 X2 cards in CrossFireX on an Intel Core 2 Quad system, powering Crysis, COD 4, and UT3 seeing the gameplay experience produced compared to a Radeon HD 3870 X2 and a Radeon HD 3870.
Introduction
The AMD ATI Radeon HD 3870 X2 was launched over a month ago. This single video card contains two GPUs with CrossFire hardwired between them; “CrossFire on a card” if you will. Both GPUs are basically Radeon HD 3870 GPUs with an elevated clock speed of 825MHz versus 775MHz on a single Radeon HD 3870. Each GPU has access to 512MB of RAM on a 256-bit memory bus, the framebuffer is not shared. In our initial testing we found the performance of the Radeon HD 3870 X2 to come in slightly behind a single GeForce 8800 GTX. This still provided a high level of gameplay experience in Crysis, COD 4 and UT3 compared to a single Radeon HD 3870.
The Radeon HD 3870 X2 supports a technology called CrossFireX. CrossFireX is AMD’s new technology that allows GPUs to be scaled up to 4 GPUs. For example you can CrossFire two Radeon HD 3870 cards in CrossFire for two GPUs worth of performance. Or, you can take the brand new Radeon HD 3870 X2 and CrossFire it with either one single Radeon HD 3870 (for triple-GPU gaming performance) or CrossFire it with another Radeon HD 3870 X2 for quad-GPU gaming performance. It is this quad GPU configuration that most enthusiasts are curious about. This is the fastest GPU combination available from AMD.
Our Focus
In this evaluation we are going to find out just what kind of gaming experience improvements quad-GPU gaming will bring to games. We will compare two Radeon HD 3870 X2 cards in CrossFireX (4 GPUs) versus one Radeon HD 3870 X2 (two GPUs) versus a single Radeon HD 3870 (1 GPU.) This will allow us to see gameplay performance scaling from one GPU, to two, to four in Crysis, COD 4, and UT3. We will be using a new quad-core CPU based platform with an Intel X48 ASUS P5E3 Premium, Intel Core 2 Extreme QX9650, and 4GB of Corsair CM3X1024-1800CD Dominator DDR3 to make sure the system will not be bottlenecking the GPUs.
Setting Up CrossFireX
Two Radeon HD 3870 X2s wait to be tortured!
Setting up CrossFire is extremely easy these days, a huge improvement over the dongle of the past. We simply installed each video card into the proper slots on our motherboard. Then, we connected both video cards with one CrossFire bridge connector. The Radeon HD 3870 X2 only has one CrossFire connector atop the card so only one bridge connector is required for operation. If you are going to be connecting one Radeon HD 3870 X2 with a Radeon HD 3870 only one bridge connection is needed as well. After that we plugged in our four 6-pin auxiliary power connectors, the 8-pin is not required for default operation.
As you can see in the pictures one of the problems you may experience is the closeness of the video cards on some motherboards. For the motherboard we are using, an ASUS P5E3 Premium, the two closest PCIe slots are used for CrossFire. In this case the video cards are right next to each other, with little room to breathe. You will want to make sure you have a good cooling solution setup in your computer; we suggest a side case fan blowing in on these cards at the least, they do get quite hot.
Driver Setup
After physically installing both video cards it is as easy as installing the driver. For our testing we are using Catalyst 8.451.2.1-080205a provided by AMD to allow for CrossFireX (quad CrossFire.) This version of the driver we were given to test with is identical in performance to Catalyst 8.3 final build according to AMD.
CrossFireX Just Works!
After a reboot we were pleasantly surprised to find CrossFire enabled by default in the CrossFire tab in CCC. We did not have to do a thing; it just simply worked, out of the box, with no trouble at all! This is by far the easiest and simplest CrossFire experience we have ever had, it just worked! As you can see four ATI Radeon HD 3870 X2s will show up in device manager.