Overclocking Controversy

It wasn’t until the Pentium II that Intel started shipping multiplier locked CPUs. Before then you could set the multiplier on your CPU to anything that was supported by the line, and if you had a good chip and good enough cooling you just overclocked your processor. Intel’s policies changed once remarking, the process of relabeling and reselling a lower spec CPU as a higher one, started to take off.

While multipliers were locked, Intel left FSB overclocking open. That would be an end user or system integrator decision and not something that could be done when selling an individual CPU. However, ever since before the Pentium III Intel had aspirations of shipping fully locked CPUs. The power of the enthusiast community generally kept Intel from exploring such avenues, but we live in different times today.

Two things have changed Intel’s feelings on the topic. First and foremost is the advent of Turbo Boost. So long as Intel doesn’t artificially limit turbo modes, we now have the ability to run CPUs at whatever clock speed they can run at without exceeding thermal or current limits. We saw the first really exciting Turbo with Lynnfield, and Sandy Bridge is going to expand on that as well. On the flip side, Intel has used Turbo as a marketing differentiator between parts so there’s still a need to overclock.

The second major change within Intel is the willingness to directly address the enthusiast community with unlocked K-series SKUs. We saw this recently with the Core i7 875K and Core i5 655K parts that ship fully unlocked for the overclocking community.

The K-series SKUs, these will be more important with Sandy Bridge

With Sandy Bridge, Intel integrated the clock generator, usually present on the motherboard, onto the 6-series chipset die. While BCLK is adjustable on current Core iX processors, with Sandy Bridge it’s mostly locked at 100MHz. There will be some wiggle room as far as I can tell, but it’s not going to be much. Overclocking, as we know it, is dead.

Well, not exactly.

Intel makes three concessions.

First and foremost we have the K-series parts. These will be fully unlocked, supporting multipliers up to 57x. Sandy Bridge should have more attractive K SKUs than what we’ve seen to date. The Core i7 2600 and 2500 will both be available as a K-edition. The former should be priced around $562 and the latter at $205 if we go off of current pricing.

Secondly, some regular Sandy Bridge processors will have partially unlocked multipliers. The idea is that you take your highest turbo multiplier, add a few more bins on top of that, and that’ll be your maximum multiplier. It gives some overclocking headroom, but not limitless. Intel is still working out the details for how far you can go with these partially unlocked parts, but I’ve chimed in with my opinion and hopefully we’ll see something reasonable come from the company. I am hopeful that these partially unlocked parts will have enough multipliers available to make for decent overclocks.

Finally, if you focus on multiplier-only overclocking you lose the ability to increase memory bandwidth as you increase CPU clock speed. The faster your CPU, the more data it needs and thus the faster your memory subsystem needs to be in order to scale well. As a result, on P67 motherboards you’ll be able to adjust your memory ratios to support up to DDR3-2133.

Personally, I’d love nothing more than for everything to ship unlocked. The realities of Intel’s business apparently prevent that, so we’re left with something that could either be a non-issue or just horrible.

If the K-series parts are priced appropriately, which at first indication it seems they will be, then this will be a non-issue for a portion of the enthusiast market. You’ll pay the same amount for your Core i7 2500K as you would for a Core i5 750 and you’ll have the same overclocking potential.

Regardless of how they’re priced, what this is sure to hurt is the ability to buy a low end part like the Core i3 530 and overclock the crap out of it. What Intel decides to do with the available multiplier headroom on parts further down the stack is unknown at this point. If Intel wanted to, it could pick exciting parts at lower price points, give them a few more bins of overclocking headroom and compete in a more targeted way with AMD offerings at similar price points. A benevolent Intel would allow enough headroom as the parts can reliably hit with air cooling.

The potential for this to all go very wrong is there. I’m going to reserve final judgment until I get a better idea for what the Sandy Bridge family is going to look like.

The Roadmap & Pricing The Test


View All Comments

  • tech6 - Friday, August 27, 2010 - link

    More speed with less power - it looks like a very competitive product. I really hope that AMD has something up their sleeve with Bulldozer and Bobcat to compete with Sandy Bridge. Reply
  • killless - Friday, August 27, 2010 - link

    17% higher performance is just not exciting.
    You need to give me 50% improvement at least to make me want to spend $1000 for new CPU/Motherboard/memory.

    It really hasn't been all that exciting since Core 2 Quad...
  • tatertot - Friday, August 27, 2010 - link

    I take it turbo was also disabled on the rest of the parts used to compare, right? Reply
  • Anand Lal Shimpi - Friday, August 27, 2010 - link

    Turbo was enabled on everything else - SB performance should be higher for final parts.

    Take care,
  • tatertot - Friday, August 27, 2010 - link


    Well that puts the IPC gains of Sandy over Westmere at something like 20% then, considering the 880 turbos up to 3.73GHz on single-threaded work.

    That's pretty impressive.
  • Drag0nFire - Friday, August 27, 2010 - link

    I just want to say first of all, this totally made my Friday! I love previews of upcoming architectures!

    Any news on the roadmap for the mobile variant of Sandy Bridge? Or do I have to wait til IDF?
  • Jamahl - Friday, August 27, 2010 - link

    What system was this benchmarked on Anand? Reply
  • Anand Lal Shimpi - Friday, August 27, 2010 - link

    Clarkdale - those charts were actually pulled from here, just with the SB numbers added:


    We didn't have the system for long enough to rerun the tests with the 5450 on the H67 board. The 5450 is GPU bound at those resolutions/settings however:


    Those numbers were generated with a Core i7 920.

    Take care,
  • Anand Lal Shimpi - Friday, August 27, 2010 - link

    I just ran a sanity check on the Core i7 880 with the 5450, the numbers don't move by more than the normal test margins - the 5450 is totally GPU bound here.

    Take care,
  • ESetter - Friday, August 27, 2010 - link

    Do you know if any of the benchmarks make use of AVX instructions? Sandy Bridge effectively doubles the maximum throughput for compute-intensive operations like SGEMM and DGEMM. While it might not translate to a 2x speedup in real-world applications, I imagine it should give a significant gain, at least in the HPC field. Reply

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