With the release of the iPhone 6S, it has come to light that Apple is splitting the manufacture of its A9 processor between Samsung, its hated rival and at the same time business partner, and TSMC, the leading chip manufacturing company in Asia. The split is said to be 60/40 in favor of TSMC.

As it turns out, the chips from the two firms are not identical. The site Chipworks, which specializes in teardowns and reverse engineering devices, notes that Samsung uses 14nm while TSMC uses 16nm.

The TSMC chip is just a bit larger – 104.5 square millimeters vs. 96 square millimeters for the Samsung chip – but it shouldn't be much of an issue because it's still the same A9 processor design from Apple. If anything, it should favor Samsung because it has the smaller chip, right?

Apparently not. One Reddit user posted tests of a pair of 6S Plus phones and found the TSMC chip had eight hours of battery life vs. six hours for the Samsung.

A second post to the Reddit iPhone board was links to a Chinese site called MyDrivers, which also ran a series of JavaScript tests and video playback tasks and watched the rates of battery depletion. Assuming Google Translate got it right, the folks at MyDrivers also saw a measurably faster battery drain on the Samsung-powered phone compared to the TSMC version.

A second set of tests showed the phone with a TSMC chip is ever so slightly faster than the Samsung chip in the benchmark tests and the Samsung chip runs a few degrees hotter.

There’s no way to tell by looking at the packaging if the phone you’re buying has a Samsung or a TSMC processor. The only way to find out is to download a free app called "Lirum Device Info Lite." You don't need the $2.99 version. Open the app and you will see basic device info on the main page. Look for where it says "Model." If your model is N66MAP or N71MAP, you’ve got a TSMC chip. If it says N66AP and N71AP, you drew the short straw and got a Samsung chip.

[Note: the author of the app has temporarily removed it from the App Store because it does not work well with new devices, according to Cult of Mac. An update is coming.]

I recently upgraded to a 6S and noticed a few things seemed off about it. For starters, it was quite hot. Second, the battery was quick to drain and slow to charge compared to the iPhone 6. I noticed this all before finding this information on Mac boards. Sure enough, I have a Samsung chip. So I guess it's back to Best Buy tomorrow before my 14 days run out.

This story has been updated to add the news about the Lirum app being temporarily removed from the App Store.

This story, "Did you get the best chip in your iPhone 6S?" was originally published by ITworld .