As you will see in our upcoming roundups, Asus has been very successful in working around the problems with the Intel Overclock lock on the 925X/915 chipsets. Abit employs similar techniques in their workaround with similar success, but Abit still tops out at about 260 with our SATA hard drive.

This screen capture of an Asus P5AD2 was made on the same core test bed used in our DDR2 memory roundup. We are using Asus BIOS version 1.05 Beta 2, but we have found that any BIOS version 1.04 or above will provide the same potential performance. CPU voltage is default 1.3875V, DDR2 memory voltage is 2.0V, and termination voltage is set to 1.2V. The video card for this screen capture is the ATI X800 XT, since any of the nVidia PCIe cards that we tested topped out at 250 -260 CPU clock.

We were finally able to determine the limit of our DDR2 memory in the unlocked Asus P5AD2. We were able to reach DDR2 733 with the just released Corsair DDR2 667 and the just-released Crucial Ballistix DDR2 667 memory. We also found that DDR2 667 branded memory, based on specially selected DDR2 533 memory chips, does indeed perform better above DDR2 683 than the DDR2 533 labeled DIMMs. DDR2 voltage was 2.0V. The DDR2 memory that we tested could not run at stock Intel settings (3:4) above DDR2 733, and the top screen capture at 278 uses a lower ratio for memory.

It should be clear by now that the simple explanations for the Overclock lock, which are circulating on the web as facts, are, at best, half-truths. To effectively reach the performance limits of DDR2 memory and current Socket 775 Prescotts on the 925X/915 requires manipulation of the PCI Express frequency at boot and the link frequency for the chipset. While increases in voltage to the chipset will allow for higher overclocks, this method does not solve the main problem of controlling PCIe/link frequencies to levels that are usable in the overclocked machine.

Breaking the Overclock Lock


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  • jiulemoigt - Saturday, July 24, 2004 - link

    I did have to laugh at #5 "Because of DDRII and the hugely overclockable Prescotts, the potential for massive Intel overclocks without extreme cooling and wads of cash would be huge." I remember the last space heater we were told would be a great thing, I think it ended up with a vacum cleaner nickname... DRII will not be faster than DRRI until they get it to the point DDRI is at now. and prescot is the reason intel requires mobo marker to design the mobo with a bolt on heatsink design... Intel survives on marketing along at this point. Reply
  • gimper48 - Wednesday, July 21, 2004 - link

    Wes, Thanks for the response man. Yeah I see what you mean. I didn't take it the same as you I was interpreting it differently. I do not see it as an argument only as a need for more testing.. Peace, Reply
  • Wesley Fink - Tuesday, July 20, 2004 - link

    #12 & #13 - I am not going to get into an argument with HardOCP, but I stand by what is posted here. I have read the [H] article and there is absolutely nothing in the article which proves otherwise to anything posted here.

    All of the testing here was with a 520W 24-pin Power Supply as already stated in the article. We found the 24-pin high-power solution with 6800 Ultra long ago - it is not a new revelation. We also reached 258-260 with the 6800 Ultra and 278 with the ATI X800XT.

    The highest result shown at [H] was 255 with either card, so the results there were not even in the same ballpark. In fact they didn't even reach the limit we found with the Abit AV8, let alone enter the new territory from 260 to 278 that is available with the Asus.
  • gimper48 - Tuesday, July 20, 2004 - link

    I forgot to include the article that the comments are refering to Reply
  • gimper48 - Tuesday, July 20, 2004 - link

    This is what one of the reviewers at had to say about this article and from what I read it seems true. More testing is definitely needed.

    Originally Posted by gimper48

    This gives some interesting insite to the overclock lock.

    And there are some things in there as well that I think are just wrong. I think his #2 statement is incorrect and so is #3. I have proven different here on our test equipment. We are OCing far beyond his 10% with no tweaks at all with a retail CPU. We saw the same issues with the engineering sample CPU.

    The SATA does have a lot to do with it though. And I do agree with his statement that ATI seems to be more tolerant, at least on the newer VPUs.

    It looks as though one thing is for sure, solid OC boards from "everyone" is not going to happen on the 925/915 front. With the latest Asus BIOS, our OCs actually got worse not better. There is still a lot of half-truths everywhere on this. That is one reason we did not get into theorizing explanations that we were not sure of backed up with limited test data using just engineering sample CPUs.
  • gamara - Monday, July 19, 2004 - link

  • dvinnen - Monday, July 19, 2004 - link

    #6 The reason for the multiplier lock was not to limit overclocking, but because some people were abusing it. They would set the multiplier of a 2000+ (or any proc) higher and sell them as a higher rated processor. There was a lot of these conterfit processors floating around last year so they had to lock it. Reply
  • tfranzese - Monday, July 19, 2004 - link

    I was already planning on an AMD64 system once PCI-E comes out w/nForce 4 chips. This just solidifies that decision at least till the fall/winter. Reply
  • mindless1 - Monday, July 19, 2004 - link

    "goodbye until you clean up your act"

    It'll happen alright, for each and every customer who shuns intel because of this... including me.
  • MadAd - Saturday, July 17, 2004 - link

    #1. "goodbye until you clean up your act"? Nah its just not going to happen. The best we can hope for is that the Intel enthusiast crowd only buy the Abit/Asus unlocked boards and put a sour taste in the finances of other mobo manufacturers that did stick to the reference design.

    Lower sales of boards, lower growth, less willingness to develop/support every sub version, less willingness to licence from intel at all yadda ya .... however if the market share of enthusiasts is as small as some make it out to be then we dont really have a choice and intel wouldn't even notice if we did say "goodbye until you clean up your act"

    Even tho some see Intel as the evil leader and AMD the underdog, I find it uncomfortable having no choice in a market of anything, even an AMD only choice.

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