The drive is no different from the older one as far as compatibility, SATA is a set standard Samsung can't really alter things.
The 860 EVO carries over the same functionality as the 850 EVO its a auto sense drive so it will play in SATA I (1.5 Gb/s), SATA II (3.0 Gb/s) & SATA III (6.0 Gb/s) systems which don't require a fixed SATA speed drive.
The real difference is the read/write performance is better with the newer drive.
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=== Update (03/20/2018) ===
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It would be wise to replace it.
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The inside surface of the uppercase are not well finished so the cable tends to wear on the rough surface. Here's the IFIXIT guide you'll need to follow: [guide|7655] and I recommend using the 2012 version of the cable [product|IF163-041-2] as its a better cable.
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Even still I would place electricians tape on the uppercase where the cable rests to help protect it. Lastly, don't over bend the bend points as you don't want to fatigued the foil conductors.
The drive is no different from the older one as far as compatibility, SATA is a set standard Samsung can't really alter things.
The 860 EVO carries over the same functionality as the 850 EVO its a auto sense drive so it will play in SATA I (1.5 Gb/s), SATA II (3.0 Gb/s) & SATA III (6.0 Gb/s) systems which don't require a fixed SATA speed drive.
* [https://s3.ap-northeast-2.amazonaws.com/global.semi.static/Samsung_SSD_860_EVO_Data_Sheet_Rev1.pdf|Samsung SSD 860 EVO]
* [http://downloadcenter.samsung.com/content/UM/201711/20171115104118871/Samsung_SSD_850_EVO_Data_Sheet_Rev_3_1.pdf|Samsung SSD 850 EVO]
The real difference is the read/write performance is better with the newer drive.