QUOTE(elliot_WD @ Aug 4 2015, 09:27 AM)
OS will only boot up faster with a solid-state drive. If you perform any operating system related task that needs to retrieve data from the drive, it will be much faster rather than the HDD. That being said, if you only care about loading subsequent programs (or logistically prefer keeping your OS separate), you can easily keep the SSD as a secondary drive, only using it for certain programs/tasks.
The whole point of a solid-state drive is to decrease application loading times. This is more due to the lower seek time rather than the faster transfer rate, which makes it more like RAM. In fact, some users would be better off getting more RAM than a solid-state drive - but that always depends on your needs.
The main storage device (SSD or HDD) is always the bottleneck of any computer system. While SSDs help to alleviate this bottleneck, new ones are still only ~1/40th the speed of RAM. For example, some memory bandwidth in newer computers has reached over 20,000 MB/s versus some new SSDs which top out at just over 500 MB/s.
You can also use it for the increased sustained transfer speed, but that only applies if you deal with very large file transfers with, for example, video encoding.
For the fastest experience with your computer, install your OS on the solid-state drive, but do remember to make frequent backups.
Hope you find this information useful.

if a system is running without ssd, the first upgrade that they should do is to add one, at least as boot drive, not adding ram. swapping hdd with ssd gets rid of the actual storage bottleneck. adding more ram to such a system doesn't help much. hdd is good for storage, but definitely not good enough as boot drive.
in a computer, ram and storage (ssd, hdd) serve different roles and purposes (temp vs. fixed storage). we don't compare them apple to apple. i personally think 500MB/s is plenty for home computing.
QUOTE(NightFelix @ Aug 4 2015, 09:57 AM)
Hey guys, I suppose to ask at "Technical Section" for sifu help, but instead of it, I check with you guys first.

In short, I want to test my Laptop whether capable to run Windows 10 smoothly or not, then later decided to wipe it and upgrade from existing Windows 8.1. So now after I wipe my partition (that contain Win10) that I split from my C drive (Is a SSD), and now I no longer able to boot my existing Win8.1, did I just done something wrong here?

SSD:
C: Win8.1
D: Win10 (after wipe this, I can't boot back to Win8.1)

HDD (Caddy):
E: Win8.1 OEM (Now I boot back into this using caddy)
it sounded like boot manager issues. you can try repair the boot manager entries using windows install media.
there is a manual way to do this (restore boot manager defaults) using bcdboot or bcdedit. this part you will need to do a search at google.