Intel Core 2 Duo: Memory Performance Part Deux

Memory Performance

Our ASRock 775Dual-VSTA motherboard provides two DDR2 and three DDR memory ratios. The ASRock 775i65G provides three DDR memory ratios although we could only get our DDR-400 memory modules to work at DDR-355 due to the front side bus ratios availability within the i865 BIOS. We are only testing this board at DDR-355 due to this issue. Our ASRock ConRoeXFire-eSATA2 board is based on the 945P chipset and features DDR2-400, DDR2-533, and DDR2-667 memory speeds. Our Biostar P965 and DFI 975X motherboards feature the same DDR2 memory speeds as the ASRock 945P board while adding DDR2-800. Even though our ASRock 775Dual-VSTA does not support DDR2-800 we are reporting these scores for comparison.

We are testing our motherboards at the fastest stable timings we can achieve and still pass our benchmark test suite. By increasing the memory voltage on the 775Dual-VSTA board we were able to run our Transcend modules at 3-4-3-9 at DDR2-667. With these set ratios, CPU speed remains the same at 1.86GHz in our test platform with memory speed being varied by selecting the different ratios.

Due to performance reasons we did not test the DDR-266 or DDR2-400 settings as we believe most people will not utilize these ratios. The balance of our comments in the first article about the Intel memory controller design and command rates with the VIA PT880 chipset still hold true. Our memory settings were derived from extensive stress testing with a variety of applications. While certain settings that allowed lower latencies worked well with some applications, the final settings we arrived at had to work with all applications.

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The Intel 865G chipset offers greater DDR memory performance than the VIA PT880 Pro in our synthetic test results. Although the buffered Intel DDR-355 scores 18% better than the VIA DDR-400 setting, the unbuffered result is only 4% better. The SuperPI test is basically a tie with the memory latency results heavily favoring the Intel chipset. Although the i865 results are well below the DDR2 based chipsets, we will see this chipset perform very well in our application and game tests.

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The Sandra bandwidth memory performance result of the VIA PT880 Pro at DDR2-533 (1:1 ratio) leads the DDR2-667 (4:5 ratio) by up to 30% although the memory timings are almost equal at both speeds. It is obvious the ASRock 775Dual-VSTA BIOS is tuned for DDR2-533. This particular setting delivered the best raw performance although we will see in our application and game benchmarks this advantage is negated by other platform components.

Overall, the VIA PT880 Pro is very competitive at DDR2-533 memory speeds with the Intel P965 showing a definite advantage at DDR2-667. The Intel 945P based ASRock ConRoeXFire-eSATA2 offers a nice balance of performance at both memory speeds while costing just $20 more than the VIA PT880 Pro board but does not allow you to use your DDR memory or AGP video card.

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Our Biostar P965 board offers a 12% improvement in the Sandra Unbuffered test, though its buffered scores are less than our DFI 975X board along with higher latencies. As we have been saying for years, however, the Buffered benchmark usually does not correlate well with real performance in applications on the same computer. For that reason, our memory bandwidth tests have always included an Unbuffered Sandra memory score. The Unbuffered result turns off the buffering schemes, and we have found the results correlate well with real-world performance as we will see shortly.