The Core i7-4950HQ Mobile CRB

At a high level, Iris Pro 5200 would seem to solve both problems that plagued Intel graphics in the past: a lack of GPU hardware and a lack of memory bandwidth. As a mostly mobile-focused design, and one whose launch partner isn’t keen on giving out early samples, it seemed almost impossible to evaluate Iris Pro in time for the Haswell launch. That was until a week ago when this showed up:

What may look like a funny mid-tower from a few years ago is actually home to one of Intel’s mobile Customer Reference Boards (CRB). Although the chassis is desktop-sized, everything inside is optimized for mobile. It’s just easier to build things larger, especially when it comes to testing and diagnosing problems.

The silicon on-board is a 47W Core i7-4950HQ, the lowest end launch SKU with Iris Pro 5200 graphics. The chassis is obviously overkill for a 47W part, but the performance we get with this machine should be representative of any i7-4950HQ system with a cooler capable of dissipating 47W.

If you read our Haswell CPU review you’ll know that Intel tried to be stingy with telling us die sizes and transistor counts for the bulk of the Haswell lineup, electing to only give us data on dual-core Haswell GT3 and quad-core Haswell GT2. Knowing that mobile parts ship without integrated heat spreaders, I went to work on pulling off the i7-4950HQ’s heatsink (after I finished testing, just in case).

With the heatsink off and thermal paste wiped off, I used my bargain basement calipers to get a rough idea of die area. This is what I came up with:

Intel Haswell
  CPU Configuration GPU Configuration Die Size Transistor Count
Haswell GT3e (QC) Quad-Core GT3e 264mm2 + 84mm2 ?
Haswell GT2 (QC) Quad-Core GT2 177mm2 1.4B
Haswell ULT GT3 Dual-Core GT3 181mm2 1.3B

The Crystalwell die measures 7mm x 12mm (84mm^2), while the quad-core Haswell + GT3 die is a whopping 264mm^2 (16.2mm x 16.3mm). Working backwards from the official data Intel provided (177mm^2 for quad-core GT2), I came up with an 87mm^2 adder for the extra hardware in Haswell GT3 vs. GT2. Doubling that 87mm^2 we get a rough idea of how big the full 40 EU Haswell GPU might be: 174mm^2. If my math is right, this means that in a quad-core Haswell GT3 die, around 65% of the die area is GPU. This is contrary to the ~33% in a quad-core Haswell GT2. I suspect a dual-core + GT3 design is at least half GPU.

Crystalwell: Addressing the Memory Bandwidth Problem The Comparison Points
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  • tipoo - Saturday, June 01, 2013 - link

    It still seems to me that this misses where it would benefit most: 13 inch laptops, which currently mostly use dual core processors. GT3e would make something like the Retina MBP 13" much more appealing for instance, but it's paired with processors such that the wattage would be too high. Reply
  • tipoo - Saturday, June 01, 2013 - link

    Oh and I wanted to ask, if the integrated graphics are disabled can the CPU still tap into the eDRAM? Reply
  • Ryan Smith - Saturday, June 01, 2013 - link

    Yes, it's a dedicated cache for both the CPU and the GPU. However it's very unlikely you're going to run into any scenario that uses a Crystalwell-equipped part in such a manner. It's not being sold in socket form, so it will go to OEMs, who in turn would only use it if they didn't include a dGPU. Reply
  • jeffkibuule - Saturday, June 01, 2013 - link

    So pretty much, unless you've got some huge beefy GPU that would absolutely suck up power compared to just using Iris Pro graphics, no one would opt for that SKU? Reply
  • shiznit - Saturday, June 01, 2013 - link

    Right on. A dual core model for the 13" rMPB would have me selling my 2012 immediately. Now I need to decide if I can live with the 15" or even bother. Reply
  • moep - Saturday, June 01, 2013 - link

    If i interpreted the results of this article correctly, I suspect that the 15" MBP is probably going to get a new and even thinner form factor with this refresh. (one chip less, fewer VRM related parts, lower combined TDP)

    A 15" rMBP approaching the weight of a 15" Macbook Air would be very interesting, although a part of me hoped that Apple would wait until Broadwell to ditch the dGPU in the 15".

    Such a step back in GPU performance with the Retina display is surely not going to be very pleasant in 3D applications.
    Reply
  • Galatian - Saturday, June 01, 2013 - link

    I actually hope/suspect, that Apple will go the other road: use a discrete graphic solution on the 15" rMBP until Broadwell comes out, but have a cTDPdown version of the 4850HQ on the 13" rMBP. Maybe they can even get the normal TDP version in there; after all it has the same (good) cooling the 15" rMBP has and I have never heard the fans on mine. I think Apple really designed it with Haswell in mind, so let's see what they'll bring on during the next few weeks. Reply
  • tipoo - Saturday, June 01, 2013 - link

    That's certainly the best case, I really hope they go down that road. The rMBP as a quad with Iris Pro would really make it worth the Pro name. Reply
  • vFunct - Sunday, June 02, 2013 - link

    They'll probably stick with the built in GPU for the 13" model and a discrete GPU for the 15" model, which is what they do right now.

    Apple's top-end MacBook Pro has always had the highest end discrete GPU available.
    Reply
  • Spunjji - Tuesday, June 04, 2013 - link

    I'm guessing you mean "for a given power usage", as there are definitely faster GPUs out there than the 650M. Reply

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