That's strange. You need two SSD's to run RAID0: http://www.tomshardware.com/reviews/ssd-raid-benchmark,3485.html. And, in fact, http://www.notebookcheck.net/Review-Acer-Aspire-S5-391-73514G25akk-Ultrabook.82547.0.html says it comes with 2 128 GB SSD's giving you 256 GB. Isn't that enough for you?
About the RAM: crucial says that all memory is soldered to the motherboard, so you can't add any. What you currently have is the maximum!
Surely you can install an other (or the same) Windows, but be sure you have all necessary software (like drivers and utilities) from the Acer site, before you erase everything on the hard disk.
Kees
Dear all:
I have some questions about hardwares of Aspire S5-391, please help me:
1. Can I replace the original SSD of S5-391(working under RAID0) with ordinary msata SSD? mine is 128gb, it is not enought for me, and I donot care about RAID workmode.
2. What the maximum capacity of SSD that the S5-391 can work with?
3. What the maximum capacity of the memory card that S5-391 can work with?
4. Can I deletel all paritions in the S5-391 that include hidden partitions and recovery paritions, then reinstall new windows.
Thank you very much for your help.

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