All the links I've found only show a single, 2.5" drive bay and no M.2 connector option.
This: http
/www.insidemylaptop.com/disassemble-asus-k-series-notebook/
A video:
https/www.youtube.com/watch?v=ZtkEm7XXNjo
If buying SSD:
1. BUY (examples):
480GB, $110USD
http/pcpartpicker.com/product/JFJwrH/sandisk-internal-hard-drive-sdssdhii480gg25
250GB, $75USD
http/pcpartpicker.com/product/3kL7YJ/samsung-internal-hard-drive-mz75e250bam
Most SSD's are fairly reliable, but do a little research anyway. If you don't need more than 200GB then I'd get the Samsung EVO.
2. BUY USB-> Sata enclosure (check customer feedback, some are crappy)
https/www.amazon.com/Inateck-Enclosure-Optimized-Tool-Free-FE2010/dp/B01FQ5R0PG/ref=sr_1_13?ie=UTF8&qid=1480452939&sr=8-13&keywords=usb+2.5%22+enclosure&refinements=p_72%3A2661618011
3. Attach SSD to USB enclosure
4. TEST the SSD
a) install Samsung Magician (Samsung SSD) or the applicable software for the SSD
b) Overprovision
c) run tests
d) update FIRMWARE for SSD if it exists (Samsung Magician can do this, but some drives may require you to find tool to check)
5. CLONE
- a few good tools such as Macrium Reflect Free
- make sure you have enough space (Windows Cleanup tool from file manager may help a lot)
http/www.macrium.com/reflectfree.aspx
6. physically SWAP drives
7. Bootup and test
8. After a WEEK or so->
a) do a full, NTFS Format of the external USB 1TB HDD
b) then create a backup IMAGE of your SSD
You can then use the remaining space on the 1TB HDD for whatever.
*You can also set Acronis True Image (non-free version) to use a USB drive for backup. You set the interval (i.e. one month) and when you attach the drive Acronis will update if the time has passed. You can also set it to DELETE older backups so basically if you set a reminder in your calendar it's pretty easy to keep a backup in case your SSD fails.
(you can even PARTITION the HDD so it's 200GB + 730GB, and put the backup images to the 730GB partition. Leave the 200GB blank. If the SSD physically fails, you can boot to the Acronis True Image CD or USB... which you must create in advance... then instruct it to RESTORE the latest backup to the first partition. In less than an hour you can be up and running, then RMA the SSD.)