Asus P5AD2 Premium: Overclocking and Stress Testing

FSB Overclocking Results

Front Side Bus Overclocking Testbed
Processor: Pentium 4 Prescott LGA 775
2.8GHz
CPU Voltage: 1.3875V (default)
Cooling: Thermaltake Jungle 502
Power Supply: HiPro 470W
Maximum OC: 280FSB (+40%)

The LGA 775 CPUs are multiplier locked, so the only way to overclock the CPU is to increase the FSB. Fixing the PCIe frequency tends to limit the overclocking of the 925X, so Asus, like others in the roundup, allows the PCI Express frequency to float. Asus then manipulates the PCIe frequency (or ratios to be more precise) during boot to achieve higher overclocks. For more information on how Asus manages to reach such outstanding overclock with the P5AD2, please check Breaking Intel's Overclock Lock: The REAL Story.

The Asus was able to reach a FSB of 280, a 40% overclock, with an ATI X800 XT and SATA hard drive. This is by far the highest overclock that we achieved with this hardware in the roundup. The P5AD2 was more limited with an nVidia 6800 Ultra video card, reaching 258. The nVidia appears to be less tolerant of out-of-spec PCIe frequency than the X800 XT.

Memory Stress Test Results:

The memory stress test measures the ability of the Asus P5AD2 to operate at its officially supported memory frequency (533MHz DDR2), at the best performing memory timings that Crucial/Micron PC2-4300U will support. Memory stress testing was conducted by running DDR2 at 533MHz (stock 3:4 ratio) with 2 DIMM slots operating in Dual-Channel mode.

Stable DDR533 Timings - 2 DIMMs
(2/4 DIMMs - 1 Dual-Channel Bank)
Clock Speed: 266MHz
Timing Mode: 3:4 (200:266 - Default)
CAS Latency: 3.0
Bank Interleave: Auto
RAS to CAS Delay: 3
RAS Precharge: 3
Cycle Time (tRAS): 10*
Command Rate: N/A
*SPD (Auto) timings for DDR2 are normally 4-4-4-12 at DDR2-533. A tRAS setting of 12 is normal. We ran a series of tests to measure memory bandwidth, and found the tRAS setting made very little difference in the performance of DDR2. The most effective range of tRAS was 8 to 13 for DDR2 on the 925X chipset, so a tRAS of 10 was chosen for benchmarking.

The Asus P5AD2 Premium was completely stable with 2 DDR2 modules in Dual-Channel at the settings of 3-3-3-10 at 1.8V default voltage. This matches the best timings that all the motherboards in this roundup were able to achieve with DDR2 memory. 3-3-3 is also faster than the specified 4-4-4 timings specified for the Crucial/Micron DDR2 modules used for these benchmarks.

Filling all four available memory slots is more strenuous on the memory sub-system than testing 2 DDR2 modules on a motherboard.

Stable DDR533 Timings - 4 DIMMs
(4/4 DIMMs - 2 Dual-Channel Banks)
Clock Speed: 266MHz
Timing Mode: N/A
CAS Latency: 4.0
Bank Interleave: N/A
RAS to CAS Delay: 3
RAS Precharge: 10T*
Precharge Delay: 3.0
Command Rate: N/A
*SPD (Auto) timings for DDR2 are normally 4-4-4-12 at DDR2-533. A tRAS setting of 12 is normal. We ran a series of tests to measure memory bandwidth, and found the tRAS setting made very little difference in the performance of DDR2. The most effective range of tRAS was 8 to 13 for DDR2 on the 925X chipset, so a tRAS of 10 was chosen for benchmarking.

As we first saw on the Abit, 4 DDR2 DIMMs are not stable at CAS 3 as 2 DIMMs are. Once again, we required 4-3-3 timings when using 4 DDR2 DIMMs, though 4-3-3 worked fine at default voltage. Perhaps more voltage could improve stability at 3-3-3 with 4 DIMMs, but our tests up to 2.0V (from default 1.8V) did not produce enough stability to complete our Super Pi or Aquamark 3 at the 3-3-3 timings.

Asus P5AD2 Premium: Features and Layout DFI LANParty 925X-T2: Features and Layout
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  • JustAnAverageGuy - Thursday, August 12, 2004 - link

    On the Gigabyte 8ANXP-D:

    Page 10

    Memory Slots Four 240-pin DDR2 Slots

    Gigabyte provides 6 DIMM slots, but the total memory and number of sides that can be used is the same as the other boards in the roundup.
  • JustAnAverageGuy - Thursday, August 12, 2004 - link

    Typo page 5:

    "The memory stress test measures the ability of the Abit AA8 to"

    should read Asus P5AD2. :)

    only on page 5, may be more.
  • l3ored - Thursday, August 12, 2004 - link

    allright, point taken. howabout testing lower lga775 cpus and combining the results with 939 scores?
  • Wesley Fink - Thursday, August 12, 2004 - link

    #5 - You're welcome.

    We also ran and reported the rest of our standard motherboard tests, which included Business and Multimedia Content Creation Winstones and Media encoding (which Intel won by a small margin).

    As we stated in the review the only reason we did not include our standard SPECviewperf 7.1.1 benchmarks is because we have seen variations of up to 100% in SPECviewperf results with certain 925X boards. We don't believe these results are real, and we are trying to find answers for these variations in benchmark results. Until we find some answers, publishing the workstation benchmark results would not really reveal anything about the performance of the 925X boards we are testing.

    The FX53, Intel 925X, and Intel 915 results are included for reference and completeness. We are comparing five 925X motherboards in performance, and we do not mean to detract from that comparison with AMD Socket 939 benchmarks. Please consider the 939 results to be a frame of reference.
  • AnnoyedGrunt - Thursday, August 12, 2004 - link

    From what I can see, the P4 560 is about $750, so that puts it right between the 3800+ (about $650) and the FX-53 (about $850) in price. It would be nice to add the 3800+ scores (if you have any) to that review just so we could see how the price/performance of the 560, 3800+, and FX-53 compare.

    -D'oh!
  • Shimmishim - Thursday, August 12, 2004 - link

    #2 - Achieving a 4 ghz overclock on a pentium is nothing to sneeze at... i think 3.8 may be possible on air but 4.2 is really pushing.

    As much as a lot of us would love to see overclocked processor results, i think it's best that they only show stock clock results as they are easier to compare...

    #3 - Its hard to say how fair it is to use a FX-53 against the 3.6 ghz 775 chip... but if you think about it, they are comparing the top end pentium 775 skt (new pin count) vs. the top of the line A64 939 skt (new pin count)..

    Both are also 1 megs of L2 even though the extra cache doesn't help the A64 greatly.

    Maybe a 3800+ would have been better comparison but i think he was trying to make things as easy to compare as possible...

    Even if he had used a 3800+ or even a 3700+ i don't think the gaming results would have been that much different... we all know that the A64's dominate in gaming.

    maybe some more tests besides gaming would have been better...

    but all in all...

    thank you Wes for a good article!
  • Wesley Fink - Thursday, August 12, 2004 - link

    #3 - The 3.6 is the fastest Intel processor. If you will check our launch reviews you will see the 3.6 outperformed the 3.4EE. We are indeed comparing the best performing Intel - the 3.6 - to the best performing AMD - FX53.

    Prior to the 3.6, the 3.4EE was the fastest Intel CPU.
  • l3ored - Thursday, August 12, 2004 - link

    lately i've been noticing unfair comparisons between intel and amd, in this article, high end processors are being compared with the top of the line from amd. this isnt really helpful to anyone, so please go back to the old anandtech way.
  • Anemone - Thursday, August 12, 2004 - link

    Nice article !

    If I could have had one extra wish it would have been to show a set of test charts with a moderate oc on them, think that would put the FX @ 2.6-2.7 and the P4 560's @ 4.2-4.3.

    If the boards can overclock, and the 939's can too, where does it all land for those using just normal or at most water oc'ing.

    No worry, these wishes do not detract from a very nice article.

    Thank you
  • stickybytes - Thursday, August 12, 2004 - link

    Nice to see asus get a award but unfourtanetly the word "prescott" mentioned in any sentence will probably scare away 80% of AT'ers.

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