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.

Overall platform performance generally favors the 975X chipset and it comes at a price, but in most cases you will need a benchmark result to see the differences. The cost, ease of overclocking capability, widespread availability, and now maturing state of the P965 products has generally been an advantage against the 975X products. However, the inability of the P965 chipset to run ATI CrossFire has been viewed as a distinct disadvantage in some circles. Whether this is truly a disadvantage or not is debatable, but for those owners wanting to run CrossFire on a capable P965 platform it has been a drawback. We also feel the inability of the P965 platform to operate in CrossFire mode has been an issue with the motherboard manufacturers who see this as an important feature on their product checklist. However, this perceived shortcoming has now changed.

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As of this week, the ability to use your ATI CrossFire setup on the P965 platform is officially supported by Intel and ATI. MSI announced ATI CrossFire capability on their P965 Platinum motherboard earlier this week. We have the board in-house for testing and just received an updated BIOS that should enable CrossFire operation. We fully expect Gigabyte and others to announce full support for ATI CrossFire on their respective P965 offerings shortly.

We digress for moment but it would also be nice to have SLI support. At this time NVIDIA SLI is not officially sanctioned on the Intel platform, although the more industrious users can run SLI with unofficial and unsupported drivers. The only official SLI platforms for Core 2 require NVIDIA chipsets which presently offer extremely poor overclocking support (typically less than 320FSB). In the meantime, can we enjoy our CrossFire experiences without worry on our P965 motherboards? That is the question we set out to answer today.

Part of that question can be answered quickly as ASUS has released the first production level BIOS that fully enables CrossFire compatibility for their P5B Deluxe motherboard. We have been testing BIOS 0706 for the last week with a beta ATI Catalyst 6.9 driver set. We found the performance to be acceptable when compared directly to the 975X based ASUS P5W-DH Deluxe but it was lacking in certain areas. We tested this BIOS with the official Catalyst 6.9 drivers and while performance and compatibility improved with the official drivers there were still some issues. The engineers at ASUS continued their round the clock efforts at enhancing the performance and released a beta BIOS to us yesterday. The performance of the 0708 beta BIOS generally resulted in overall performance improvements of 3%~9% in our testing. While both the ATI driver and ASUS BIOS still have room for incremental performance improvements, the initial results we will show today are indicative of this platform combination.

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 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.

Test Setup and Synthetic Graphics
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  • Madellga - Monday, September 25, 2006 - link

    Coolaler has posted on XS some benchmarks for SLI on 975 and 965 chipsets.
    True, there are small differences between the setups (FSB and multis), but CPU speed was close enough.

    You can see an impact between 15% and 20% for going from the 975 to 965 when running SLI with hacked drivers.

    This other thread has SLI on the 965 for a 7600GT, but no comparison to the 975
  • Gary Key - Monday, September 25, 2006 - link

    I have seen basically the same results in internal testing here, just that I cannot publish those numbers. ;-)
  • Maruta731 - Saturday, September 23, 2006 - link

    It will be worthwhile to test the X1900GT and X1800GTO. Dongle-less Crossfire depends entirely on the PCIe interface for inter-card communication; it may expose a significant bottleneck in the 965 board's PCIe x4 slot. And realistically, many users who decided to save a few bucks with a 965 board will probably want to use these mainstream cards.

    I have also heard somewhere that running two X1900GTs in Crossfire requires a RD580 board. Always wondered if it's true, because then Conroe users effectively lose this option.
  • Gary Key - Monday, September 25, 2006 - link


    It will be worthwhile to test the X1900GT and X1800GTO.
    I will get a board up to Derek for further testing shortly. I do not have the dongle-less CrossFire cards at this time.
  • jive - Monday, September 25, 2006 - link

    Interesting phrase, as I thought SLI is not officially supported on any of these two platforms:

    This simply means that as games become increasingly complex and data bandwidth increases then the differences between the P965 and 975X in CrossFire or SLI operation will widen.

    Any comments?
  • Gary Key - Monday, September 25, 2006 - link

    This was more of a forward looking statement (already addressed the unofficial SLI driver situation) and also to address any issues with readers saying they can run SLI on their Intel boards now. If NVIDIA and Intel ever come to an agreement then the statement holds true, if you decided to run the unofficial SLI drivers on the P965 then the overhead from the hacked drivers along with the DMI slowdown will create a performance delta between the 975X and P965.
  • Madellga - Saturday, September 23, 2006 - link

    Gary, nice article. I think it is the first time I see a comparison on the performance hit caused by the x4 bottleneck. It would be interesting also to see in a future article how does a pair of 7900 GTXs running in SLI using the hacked drivers stacks against the XFire solution.

    I wonder if this move will drive Nvidia in the future to allow also SLI on the 975 or 965 chipsets. We know it can be done, perhaps it is a commercial or licensing problem that is blocking it.
  • nlr_2000 - Sunday, September 24, 2006 - link

    But like the article pointed out, it's not the x4 PCIe slot but the interface between the Northbridge/Southbridge causing the performance hit.
  • formulav8 - Saturday, September 23, 2006 - link

    Please bring back the bar graphs. That is all.

  • Frumious1 - Saturday, September 23, 2006 - link

    Hell no! Not for this type of article - leave the scaling graphs in place. I would much rather see one graph (with numbers below) showing how cards scale from 1280x1024 through 1920x1200 instead of three separate graphs. Single bar charts are only effective when showing one data set.

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