(For techies) Why Broadwell Graphics Performance could be 40% or more over haswell

Discussion in 'MacBook Pro' started by linjac321, Dec 5, 2014.

  1. linjac321 macrumors newbie

    Dec 5, 2014
    So everybody is expecting broad well. Its certainly coming early 2015 from apple. Probably late January early february. Great way to start off the year, right guys? Anyways, the reason I know that the graphics performance would increase by 50% for the retina macbook pro is because the graphics tdp will drop by half.

    So if you don't know. tdp is thermal design power. its how they measure how big to make the heatsink and such. If you don't know apple as well as i do, then you'll know in order to get the maximum tdp of your chip, you will have to burn your cpu to 100C. Unlike other companies who keep it around 70C, which is nominal, apple likes to push their laptops to its limits in order to get thinner and more battery.

    The tdp of the graphics card for ivy bridge was 45W. So in order to get the full performance out of the graphics on ivybridge you would have to have heat sink that can take care of 45W of power. obviously at the time, macbook pro had a 35w limit and the air had 17w limit. Haswell dropped that power to 30W. which is almost 33% faster in graphics performance based on tdp alone +15~20% in the architectural change. Keep in mind though the tdp limit for the 13.3" models is 28w so the macbook has to share cpu power and gpu power to achieve the maximum performance of the gt3 architecture. rMBP cpu can take up to 20-22W of the 28W allowed. so basically in order to achieve full combined performance the tdp limit should be 22+30+4(this is for the pch controller now integrated in the chip itself)=56W TDP.

    The New Broadwell CPU is now 15W TDP for the graphics. so lets say they keep the same 28W tdp limit. 28W-4W = 24W available to share between the CPU and GPU. 15(GPU)+17W(CPU (based on my estimates making the cpu more efficient)) + 4W PCH= 36W of TDP is need for maximum combined performance. 28W/36W is only 80% of away from peak performance. Where as 28/56W is 50% away from peak performance. 30% increase in peak performance. 10% more peak performance could could from the l4 cache integrated for the graphics. its like a memory buffer for the graphics card. this helps a lot because the memory they use in graphics cards are way more sophisticated and powerful than the shared video memory we use for day to day operations. it won't be as fast as the dedicated graphics in memory performance, but will certainly close the gap.

    I am talking about the 13.3" rMBP and the 6100 iris that will coming for it.

    Highly opinionated Information. Please be easy on me.
  2. ChrisDB macrumors member


    Oct 29, 2014
    Bucharest Romania
    Even with that performance increase , integrated graphics cannot handle the retina display properly . OS X algorithms for the retina needs video memory otherwise the ui lags .

    It's a shame because windows doesn't have this problem and can handle even bigger resolutions with less powerful hardware .
  3. linjac321 thread starter macrumors newbie

    Dec 5, 2014
    I think it should handle retina if it already did. The 6100 irish should be comparable if not beats the 5200 pro. This is because they are adding the edram into the chip. edram is the key into making retina work on integrated graphics. This is why you don't hear anybody complaining on the retina macbook pro. there are two versions the one with 750m and the one with 5200 iris pro only. And the 15" packs more pixels than the 13"
  4. maflynn Moderator


    Staff Member

    May 3, 2009
    Are you sure the UI lag is directly related to the iGPU and not OS X, or one of its drivers?

    I think the current state of iGPUs, the Iris Pro is more then up to the task to drive the retina display. I'm content with my old 2012 model, its on the iGPU when ever I can, and I'm happy with the performance.

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