Microsoft Surface Pro series facing heavy throttling issues
The Surface tablets are arguably some of the best Windows tablets currently available and they frequently top our own Top 10 lists. Unsurprisingly, we were quite excited to finally be able to test the Surface Pro and run it through our usual suite of benchmarks. What was surprising, however, were some of the performance results we discovered.
Surface Pro 2017 Core i5-7300U
Our first Surface Pro model was the Core i5-7300U SKU and, as shown by our looped CineBench R15 Multi-Thread test scores below, CPU performance can fall significantly from 334 points during the start of the run to as low as 226 points towards the end. This represents a drop of almost 33 percent from what we expect out of a proper ULV Core i5-7300U. In fact, such behavior is more common on a 4.5 W Intel Core Y or Core M series CPU rather than a 15 W Core U series.
It's important to note that most notebooks sporting Intel U-class CPUs utilize active cooling solutions. Microsoft's decision to completely omit a system fan on the Core i5-7300U SKU will mean that Turbo Boost performance can be severely limited. The higher clock rates are only beneficial for the first minute or so before reaching an imposed temperature ceiling. Our tests show that once the CPU reaches around 57 C, clock rates will throttle to 2.3 GHz or slower in order to maintain safe operating temperatures.
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Surface Pro 2017 Core i7-7600U
So, what about the costlier SKU with the Core i7-7600U CPU?
The i7-7600U configuration gave us hope because it features an active fan compared to the fanless Core i5-7300U SKU. While our tests are still ongoing, we can already confirm that the processor will throttle just as heavily when under the same CineBench R15 Multi-Thread loop test as shown by our graph below. Scores drop steadily after each subsequent run from 410 points down to 340 points by the 7th or 8th loop. This means that users who purchase the Core i7-7600U SKU will actually have a performance level closer to that of a proper Core i5-7300U CPU instead of the Core i7 that they paid for.
Microsoft's promise of a 50 percent performance boost over the Surface Pro 4 generation is only partially true. Our tests on both the Surface Pro 2017 Core i5 and Core i7 SKUs reveal that performance is indeed faster, but only for the first few minutes before throttling inevitably kicks in. Microsoft is essentially overcharging for the Core i5 and Core i7 configurations since their respective cooling solutions are clearly unable to maintain the proper base clock rates that we have come to expect from a U-class processor. Fortunately, the new Surface Laptop Core i5-7200U SKU exhibits no such throttling issues, but this still leaves a very sour taste in our mouth about how the Surface series is being handled and marketed.