12-18-2020, 08:28 AM
https://www.extremetech.com/computing/31...ed-version
Quote:The first thing I want to say here is that the Intel Iris Xe Max is not marketed as a gaming GPU, even though it’s a discrete solution. It is, however, identical to the well-received 11th Gen integrated GPU, and should therefore have at least some basic gaming capabilities. Our sister site PCMag recently took a laptop equipped with an Iris Xe Max for a spin, and what they found was rather odd.
The Iris Xe Max is Intel’s first discrete GPU in many years and it sports 768 cores, 48 TMUs, and 24 ROPS (768:48:24). It uses LPDDR4X to keep power consumption down, instead of GDDR, and it offers a 128-bit memory bus, with a 4GB RAM buffer. Intel’s latest full-fat integrated GPU, the Xe Graphics G7, is built into chips like the Core i7-1185G7, also have a 768:48:24 configuration.
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These results are odd. We’re comparing two GPUs based on identical GPU cores. The discrete card has every advantage — dedicated RAM, higher core clocks, higher overall memory bandwidth — and yet it can’t win. Why not?
Let me say upfront that the answer might be something banal, like “Dell shipped the laptop with an early graphics driver,” or “A firmware update improved CPU and GPU performance by tweaking throttle points.” A more interesting possibility is that we’re seeing the impact of differences in power management and thermal targets between the Dell and the Intel whitebook, or, a performance-limiting characteristic of LPDDR4X. The penalty would have to be enormous — the Intel whitebook has a large lead in some of these tests. This seems unlikely.
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When it comes to OEM laptops, Intel allows manufacturers to target a wide range of skin temperatures and thermal targets. Many of Intel’s chips can be configured for a TDP of 12W – 28W depending on how the manufacturer wants to position a specific system. Manufacturers also have wide latitude in terms of the cooling solutions they build into their hardware and the degree to which they specifically optimize component placement to ensure the fastest system with the least amount of throttling possible.
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This PCMag benchmark from Ice Lake’s debut makes the point. Two of the three Core i7-8565U-powered machines score almost identically. The third is much faster. It’s possible that Dell picked less aggressive thermal and power targets than Intel did, either for the CPU, GPU, or both. It’s also possible that Intel’s Core i7-1185G7 is more aggressive when it comes to maintaining boost clocks and runs faster in 720p for that reason. I checked other reviews on Tiger Lake laptops, and the GPU performance on those systems was only a little slower (1-2 fps) than the whitebook.
One of the reasons I suspect there might be a power or thermal issue in play here is because of what happened back when Intel launched Core M. There were three Core M CPUs to choose from, and folks soon noticed that the lowest-end CPU sometimes ran faster than the higher-end chips. While the higher-end chips had a higher boost clock, they hit their thermal trip points much more often and had to throttle back. It’s possible that the dGPU is either ramping up and down, or that other thermal limits in the chassis keep its overall clock rate lower.
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This is not a terribly strong debut for the Iris Xe Max. Intel wants to sell this card as an AI and machine learning accelerator, and it has a technology called Deep Link built into the chip that will allow the iGPU and dGPU to team up on certain workloads. At the same time, Tiger Lake’s biggest performance jump is in graphics, where Intel managed to take the overall performance lead from AMD. It would be incoherent to simultaneously praise Tiger Lake’s integrated performance while pretending the Iris Xe Max isn’t built from the same silicon and shouldn’t offer at least the same performance.
Hopefully, there’s a combination of improvements that will at least bring the performance of the Iris Xe Max up to match the Core i7-1185G7’s baseline. Intel isn’t marketing the Iris Xe Max as a gaming GPU, and we can’t evaluate it as an AI/ML accelerator using Deep Link yet, because the feature isn’t supported in any software, but customers who buy Iris Xe Max silicon shouldn’t be penalized with slower GPU performance compared with integrated users, even if that’s a relatively modest amount in the grand scheme of things.