ED#211 : The ASUS ZenPad 7.0's True CPU Speed

In our review of the ASUS ZenPad 7.0, we pointed out that it was powered by a quad-core Intel Atom x3-C3230 SoC running at 1.2 GHz. However, we noticed that it was much slower than the ASUS ZenFone 2 in both work performance and 3D graphics.

At first, we chalked that up to the ASUS ZenFone 2's faster quad-core Intel Atom Z3580 processor. The disparity was a lot more than what we expected, so we dug deeper. Then we discovered that it was slower for a much different reason.

Intel officially rates the Atom x3-C3230 SoC to run at 1.2 GHz, but ASUS never specifically claimed that they were running it at 1.2 GHz. The ZenPad 7.0's specifications only list the CPU as the Intel Atom x3-C3230, with no mention of the actual clock speed.

Based on our investigations, it looks like ASUS set the ZenPad 7.0's Atom x3 processor to run at only 900 MHz. The 25% slower clock speed could explain its larger than expected performance gap vis-à-vis the ZenFone 2. Take a look at our test result...

The ASUS ZenPad 7.0 (Z370CG) Tablet Review

CPU-Z

CPU-Z lists the processor as running between 416 MHz and 900 MHz.

3DMark

In this graph, you can see that even when the ZenPad 7.0's CPU is maxed out, it only runs at 900 MHz.

Geekbench 3

Geekbench 3 also lists the ZenPad 7.0's CPU speed as 900 MHz.

Antutu Benchmark

Antutu Benchmark backs up CPU-Z, listing the ZenPad 7.0's clock speed as between 416 MHz and 900 MHz.

What Does This Mean To Us?

We should note first of all that ASUS never mentioned the clock speed of the Atom x3-C3230 processor used in the ASUS ZenPad 7.0. We reviewers just assumed that they would be running the Atom x3-C3230 processor at its maximum rated clock speed.

They likely underclocked the Atom x3-C3230 processor to reduce its thermal output and extend the ZenPad 7.0's battery life. That would explain how ASUS managed to get the ZenPad 7.0 to last 4.5 hours on the PCMark battery stress test, and about 6 hours in real world usage, using just a 2,600 mAh battery.

It would also explain why the ZenPad 7.0 runs relatively cool even when we stress it using benchmarks. It only gets warm where the Atom x3-C3230 is located - a surface temperature of about 42.5°C at full load.

As far as the ASUS ZenPad 7.0's performance is concerned, this revelation changes nothing. It is still as fast as it was before our revelation, with the same battery life and the same capabilities. The only thing it changes is the clock speed specifications of the ZenPad 7.0 tablet in our review.

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