ASUS P5B Deluxe: ATI CrossFire and Intel P965 Tango

Zarolho

Power Member
We previewed the ASUS P5B Deluxe in our Conroe Buyers Guide and were impressed with its features and performance even though we had a very early BIOS release. However, the launch price of near $250 placed it squarely in the middle of the 975X chipset boards that offered equal or better performance along with additional features such as ATI CrossFire support and, more importantly, maturity. Honestly, the entire P965 launch was premature and was fraught with performance and memory compatibility issues. Over the past couple of months ASUS has worked diligently at enhancing the performance of the board along with providing greatly improved memory compatibility. This same situation has held true with the vast majority of Intel P965 based motherboards and we are just now getting to the point of accepting the P965 platform as a logical choice for the entire Core 2 Duo processor range.

One interesting feature of the more performance oriented P965 motherboards has been their ability to overclock up to 550FSB on a regular basis, something the 975X motherboards cannot do at this time. In fact, we expect to see stable 600FSB (2400 MHz quad-pumped) plus levels coming in the near future on the P965 platform. While this is certainly impressive, memory bandwidth suffers in certain FSB ranges as the memory controller strap changes introduce additional latencies along with a reduction in the MCH clock speed. We will delve into this subject matter in our upcoming P965 roundup but additional details can be located here.

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ASUS will release their official performance enhanced CrossFire capable BIOS early next week. The BIOS will be version 0709 and will include their new C.G.I. technology. ASUS C.G.I. stands for ASUS Cross Graphics Impeller (is anybody awake in marketing?) and is a feature that if enabled will automatically optimize system performance if a CrossFire configuration is detected. The optimizations occur within the Direct Media Interface between the P965 MCH and ICH8R that is utilized to enable CrossFire operation. The 975X chipset utilizes Peer-to-Peer write capability within the MCH to enable 2x8 PCI Express lane capabilities for CrossFire. This feature is not available in the P965 so ATI enables CrossFire support utilizing the Direct Media Interface (DMI) to link the x16 GPU slot (16 PCI Express Lanes) residing on the MCH and the x4 GPU slot (4 PCI Express Lanes) residing on the ICH.

In theory, you should be able to load the Catalyst 6.9 drivers on any P965 motherboard that contains the required x16/x4 PCI Express slot layout and start using CrossFire. It turns out for the motherboard manufacturers that certain BIOS calls need to be implemented for this to occur properly and these same BIOS settings need to be optimized for improved performance. We have not tried all of our CrossFire capable P965 motherboards at this time but so far the three we have tested require BIOS updates for proper CrossFire operation. This leads us into today's preview, so let's take a closer look at how the Intel P965 compares to the 975X chipset in CrossFire performance.

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Quick Take

Our experience to date with CrossFire capability on the ASUS P5B Deluxe board has been surprising to us. We expected a lot less performance along with a lot more issues. We are in the middle of doing compatibility testing on over three dozen games at this time and so far the vast majority have worked flawlessly. While not having OpenGL compatibility is disappointing, we can understand why ATI has chosen to remove this feature until they can guarantee performance and stability in OGL games. We are more concerned about the lack of HDR CrossFire capability in an older title like Half Life 2; hopefully this can be corrected quickly, or it might be a system/motherboard specific issue. We are still testing this title along with Episode One and should have a resolution shortly. In regards to the Company of Heroes issue, until we hear back from ATI it will be difficult to determine if it is a driver or game issue. It was not until the 1.02 patch that SLI worked properly with the game so we will give ATI the benefit of doubt at this time, even though CrossFire worked perfectly on the 975X based ASUS P5W-DH Deluxe board.

Overall, a three to nine percent performance hit in our limited testing is not that bad, although the more performance minded enthusiasts will likely consider the 975X boards for CrossFire performance. However, with the recent price reductions on the Asus P5-B Deluxe this board becomes an attractive alternative. We believe ASUS has done a remarkable job in such a short period of time in getting a CrossFire capable BIOS ready for the P5B Deluxe. We also have to give credit to ASUS as within a couple of days after the initial bios release they were able to enhance performance and implement a CrossFire auto-sensing function to enable DMI optimizations. These optimizations directly led to performance improvements of up to 9% in most of our game titles compared to the previous bios. Hopefully, they will have optimizations ready for CrossFire solutions other than the X1900 and X1950 shortly. We still have a significant amount of testing to complete but at this time it appears ATI CrossFire works as advertised on the P965 platform and maybe just that much better on the ASUS P5B Deluxe.

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