Overclocking and 22nm

In the old days, whenever Intel transitioned to a new manufacturing process it was accompanied by increased overclocking headroom thanks to the reduction in power consumption and increase in switching speed afforded by the new transistors. To be honest, it's surprising the ride has even lasted this long.

Intel's 22nm process (P1270) is the most ambitious yet. The non-planar "3D" transistors promise to bring a tremendous increase in power efficiency by increasing the surface area of the transistor's inversion layer. It's the vehicle that will bring Intel into new form factors in mobile, but we're around a year away from Haswell's introduction. Rather than 22nm being a delivery platform for Ivy Bridge, it feels like Ivy Bridge is being used to deliver 22nm.

The process is still young and likely biased a bit towards the lower leakage characteristics of lower voltage/lower wattage CPUs, such as those that would be used in Ultrabooks. These two factors combined with some architectural decisions focused on increasing power efficiency result in what many of you may have heard by now: Ivy Bridge won't typically overclock as high as Sandy Bridge on air.

The frequency delta isn't huge. You'll still be able to hit 4.4—4.6GHz without resorting to exotic cooling, but success in the 4.8—5.0GHz range will be limited to water alone for most. Ivy Bridge is also far more sensitive to voltage than Sandy Bridge. Heat dissipation can increase significantly as a function of voltage, so you'll want to stay below 1.3V in your overclocking attempts.

Dr. Ian Cutress, our own Senior Motherboard Editor, put Ivy Bridge through a pretty exhaustive investigation if you want more details on exactly how the chip behaves when overclocking and how best to overclock it.

For the past few years I've been focused on power efficient overclocking. I'm looking for the best gains I can get without significant increases in core voltage. With my 3770K I was able to reliably hit 4.5GHz with only a 140mV increase in core voltage:

The end result is a 15—28% overclock, accompanied by a 32% increase in power consumption. The relationship between overclock speed and power consumption actually hasn't changed since Ivy Bridge, at least based on this datapoint.

Ivy Bridge Overclocking
Intel Core i7 3770K Stock 4.6GHz Overclock % Increase
Load Power Consumption 146.4W 204W 39.3%
x264—2nd Pass 41.8 fps 49.5 fps 18.4%

As always, your mileage may vary depending on the particular characteristics of your chip. Ivy Bridge can be overclocked, but at least initially it's not going to be as good of an overclocker as Sandy Bridge. Over time I expect this to improve somewhat as Intel's 22nm process matures, but by how much remains a question to me. It's unclear just how much of these limits are by design vs. a simple matter of process maturity.

Die Size and Transistor Count The 7 Series Chipset & USB 3.0
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  • ijozic - Thursday, April 26, 2012 - link

    Maybe because people who prefer to have the IPS screen would also like to have support for graphics switching to have a nice battery life while not doing anything GPU intensive. This was the one thing I expected from Ivy Bridge upgrade and NADA. Reply
  • uibo - Monday, April 23, 2012 - link

    Does anyone know if the 24Hz issue has been resolved? Reply
  • uibo - Monday, April 23, 2012 - link

    nevermind just saw the htpc perspective review Reply
  • anirudhs - Monday, April 23, 2012 - link

    I didn't notice that issue. 23.976*1000 = 23976 frames, 24 * 1000 = 24000 frames, in 16 mins 40 secs. So that's about one second of mismatch for every 1000 seconds. I could not notice this discrepancy while playing a Blu Ray on my PC. Could you? Reply
  • Old_Fogie_Late_Bloomer - Monday, April 23, 2012 - link

    Okay, well, I'm pretty sure that you would notice two seconds of discrepancy between audio and video after half an hour of viewing, or four seconds after an hour, or eight seconds by the end of a two-hour movie.

    However, the issue is actually more like having a duplicated frame every 40 seconds or so, causing a visible stutter, which seems like it would be really obnoxious if you started seeing it. I don't use the on-board SB video, so I can't speak to it, but clearly it is an issue for many people.
    Reply
  • JarredWalton - Monday, April 23, 2012 - link

    I watch Hulu and Netflix streams on a regular basis. They do far more than "stutter" one frame out of every 960. And yet, I'm fine with their quality and so our millions of other viewers. I think the crowd that really gets irritated by the 23.976 FPS problems is diminishingly small. Losing A/V sync would be a horrible problem, but AFAIK that's not what happens so really it's just a little 0.04 second "hitch" every 40 seconds. Reply
  • Old_Fogie_Late_Bloomer - Monday, April 23, 2012 - link

    Well, I can certainly appreciate that argument; I don't really use either of those services, but I know from experience they can be glitchy. On the other hand, if I'm watching a DVD (or <ahem> some other video file <ahem>) and it skips even a little bit, I know that I will notice it and usually it drives me nuts.

    I'm not saying that it's a good (or, for that matter, bad) thing that I react that way, and I know that most people would think that I was being overly sensitive (which is cool, I guess, but people ARE different from one another). The point is, if the movie stutters every 40 seconds, there are definitely people who will notice. They will especially notice if everything else about the viewing experience is great. And I think it's understandable if they are disappointed at a not insignificant flaw in what is otherwise a good product.

    Now, if my math is right, it sounds like they've really got the problem down to once every six-and-a-half minutes, rather than every 40 seconds. You know, for me, I could probably live with that in an HTPC. But I certainly wouldn't presume to speak for everyone.
    Reply
  • anirudhs - Tuesday, April 24, 2012 - link

    I will get a discrete GPU and then do a comparison. Reply
  • anirudhs - Monday, April 23, 2012 - link

    a discrete GPU! I could use a bump in transcoding performance for my ever-growing library of Blu-Rays. Reply
  • chizow - Monday, April 23, 2012 - link

    Looks like my concerns a few years ago with Intel's decision to go on-package and eventually on-die GPU were well warranted.

    It seems as if Intel will be focusing much of the benefits from smaller process nodes toward improving GPU performance rather than CPU performance with that additional transistor budget and power saving.

    I guess we will have to wait for IVB-E before we get a real significant jump in performance in the CPU segment, but I'm really not that optimistic at this point.
    Reply

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