Since the first reports of Intel's overclock lock, the web has been buzzing with speculation about what Intel did and how to fix the lock. There has been so much misinformation, partial truths, and downright confusion regarding the lock that it's time to set the record straight.

Asus and Abit have been most successful so far in finding ways around the lock, so we spent some time with both companies to determine what they have found and how they are bypassing the lock. How do we measure success? It is simply a matter of performance. Abit has managed to produce a 925X that is capable of a 258 CPU Frequency.

Click to enlarge.

Asus has enjoyed even more spectacular success. With their latest BIOS revision 1.04 and higher, Asus is now reaching our CPU limit of 278-283 CPU frequency. This is confirmed with a SATA hard drive and PCIe video card, since you will see there is much more to the story than Northbridge voltage.

Yes, Virginia, There IS an Overclocking Lock

The overclock lock is very real on the Intel 925X/915 chipset. Sources close to Intel have confirmed that the 925X/915 chipset was designed with a 10% overclock limit as a design parameter. This is not a simple lock loop, but involves several components according to Engineers at Asus and Abit:
  1. PCI Express floats in the Intel 925X/915 chipset. PCIe frequency exceeds the capabilities of PCIe cards at about the 10% overclock level. Neither Asus or Abit or any other manufacturer that we have talked with has been able to effectively lock the PCIe frequency in the new 925X/915 design. This is the major roadblock to overclocking on the 925X/915, as any attempt to lock the PCIe frequency limits overclocking.
  2. The Northbridge and Southbridge link frequency also floats with the CPU frequency, and since link frequency is monitored at startup, values higher than 10% cause system shutdown. It is true that increasing the voltage to the chipset increases tolerance in this area, but you only gain about 10 MHz to 15 MHz by applying voltage (CPU frequency can increase from 220 to 230 to 235), since the PCIe and SATA issues are not corrected.
  3. SATA must be fixed at 100 to function, but the SATA frequency is also influenced by the link frequency. SATA drives simply disappear when the link frequency exceeds the 10% overclock. This can be extended with a bit of voltage, but voltage is not a fix for this issue either.

Breaking the Overclock Lock


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  • danidentity - Saturday, July 17, 2004 - link

    It's only a matter of time until AMD starts limiting overclocking just as Intel is doing now. Don't forget how Intel used to be the only one with locked multipliers. AMD then followed suit.

    Anand, do you plan on doing an article to see how well the off-the-shelf LGA775 chips themselves scale with OCing?
  • neologan - Saturday, July 17, 2004 - link

    #4, i do not agree. Because of DDRII and the hugely overclockable Prescotts, the potential for massive Intel overclocks without extreme cooling and wads of cash would be huge. They are trying to limit this as much as possible - that is what the lock is for. They are not doing this out of spite just because enthusiasts are not picking there platform, they are doing it because if there was no lock, we would be seeing massive overclocks at low prices of the likes we have never seen before. Intel can go to hell imo....AMD all the way. They have, for a long time either provided amazing value and competitive performance, or equal prices with better performance. Reply
  • Anemone - Saturday, July 17, 2004 - link

    Because when the 875 was around Intel had a competitive set of cpu's. Now, Intel figures that those in the know aren't buyng their cpu's. There are easily a dozen websites that are recommending AMD64 when it comes to current machine builds. So Intel figures the only ones buying their machines are the Dell purchasers of the world. If that is true then why build a chipset that helps enthusiasts?

    I get the strong feeling that Intel doesn't feel they CAN compete anymore in the enthusiast arena, that each time they release a more competitive CPU, AMD will just one up them. So, they are figuring why bother. Remember Intel is lead around by the marketing department. They lock things down, and get two results. They guarantee a simple, solid non overclocking chipset, thus making sure that the people buying their stuff are the run of the mill types who will upgrade when Intel tells them to. Secondarily they then put their own branded motherboards in a better light so they get that revenue stream ticked up a bit, when the enthusiasts pretty much stop buying their high end cpu's. They think that's a win in the end for them and carries them in the best way through the "strong AMD" bad times which they figure they'll get back under control in 2005. Then they can release a more overclocker friendly chipset, get everyone happy again, and put the market back the way they want it.

    Yep corporate types really do plan for this sort of thing.

    If they wanted every enthusiast out there to choose AMD this time around, looks like they've succeeded. Good job Intel! (sarcasm)

    And you wonder why many of their top engineers are leaving the company? hehe Hint, it's not rocket science...
  • Pumpkinierre - Saturday, July 17, 2004 - link

    Dont understand why you wouldnt get the same SATA failure with the i875/865 when you overclock? The link must also increase in speed when the FSB is increased but I have'nt heard of SATA failures on these mobos with overclocking.
  • zShowtimez - Saturday, July 17, 2004 - link

    Never thought it would come to it but so far its lookin like my next rig will be AMD. Reply
  • Anemone - Friday, July 16, 2004 - link

    You know, in 4 months Nvidia will have the NF4 with Pci-e for a chip that genuinely performs.

    Oh, don't take this wrong, P4's perform too but you have to give them some oomph to get things moving on them. And if Intel is dead set on making this impossible, then why don't enthusiasts just switch? Since Pci-e can't be locked but only run in 'tolerable' specs, then you know you are stressing your peripherals, something that modern chipsets were supposed to have left behind over the past few years.

    Intel I guess didn't learn their lesson with RDRAM, and think that telling the user community how they want things done is acceptable.

    Personally I don't like that attitude. I don't care for what they consider calling a competitive price for a lower performing chip, and I think it's high time the user community gives them the same message it gave them over the memory issue, "goodbye until you clean up your act"

    For me, I think this about does it. We'll see if others feel the same.


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