MSI GT70 0NC 494 - Samsung 840 Evo Problem

Question

I recently brought a Samsung 840 Evo 500GB to replace the WD Black HDD on my MSI GT70-0NC-494 laptop. OS is Windows 8. Im going type out pretty much how I ended up to where I am right now in hopes that maybe someone could catch where I went wrong.
So here's the story:
The cloning process went smoothly and I was able to load the OS from the SSD without any problems. Then I immediately updated the firmware and I set the optimizations using the Magician software.
I ran CrystalDiskMark and had speeds around ~300MB for both read and writes on the sequential test. Thought that my speeds were kind of slow when comparing them to the others I've seen. AHCI is on. I know my laptop has a SATA 2 and SATA 3 slot but I did plug the SSD in the SATA 3. SATA 3 connection is confirmed through Intel RST application and Samsung Magician. The speed is just not around the ballpark of what everyone is getting.
Ok, let's see the speeds with Rapid Mode so I turned on Rapid Mode and restarted. Then I get a "Start PXE over IPv6/4" message which then leads to the BIOS screen. Turn off laptop, turn it on, and get the same message. Turn off laptop again, turn it on, and the OS loads this time.
I thought that was weird but whatever I got to the OS, I thought. Open up Task Manager to see how Rapid Mode affects my RAM capacity since my regular usage already puts me ~1.5GB below max. 1.9GB shows up on RAM. Thought I'd be starting closer to 3GB. Then again, Im not entirely sure on how Rapid Mode works so whatever. Run the benchmark test through Magician software.
(This pic was from after I reinstalled Win 8 but the performance drop was similar)
Ok, , the read speeds is now garbage. Did the test on CrystalDiskMark and it shows similar results. It was late at night and Im feeling tired so I keep my laptop idle overnight to see if that would help. Nope, read speeds are still garbage. Surprisingly enough, CrystalDiskMark would show write speeds for sequential hitting ~1000MB/s so it seems that the write process is somewhat fine. The read process seems like it's broken.
So I turn off Rapid Mode and see if that fixes my read speeds. Restart. Get BSOD on startup. Turned laptop on and off multiple times to see if anything works but no avail. Thankfully I created a set of recovery disks 2 days ago so I immediately run that now. I was planning to restore the OS to factory install anyways so its fine.
OS is restored. At this point Im scared of installing the Samsung Magician software so I make a restore point. This time I want to see what happens if I install the software and run Rapid Mode through Win 8.1.
Seems like I can't just upgrade to 8.1 without installing a bunch of updates first so I do that. I got impatient so I went ahead and installed Magician and did the optimizations. CrystalDiskMark showed ~300MB/s for read and ~400MB/s for write. Ran the Magician benchmark and it produced the light blue bars on the screenshot above.
Let's try Rapid Mode now. Turn Rapid Mode on, restart, and I am again greeted with the "Start PXE over IPv6/4" message before hitting the BIOS. Now Im telling myself that I messed up again. Turned off the laptop and turned it on. OS is back. Awesome, only 1 try.
Did benchmarks on Magician which again showed that my read speeds were garbage (dark blue bars). I'm not even going to touch Rapid Mode for fear of having to reinstall the OS again. So now Im trying to upgrade to Win 8.1 and see if that fixes something.
Download 8.1, restart, I get some BSOD message with the code "0xC1900101 - 0X20017", restart through BIOS, and I get an error saying that 8.1 failed and Im being reverted to 8. Desktop loads up, I check Magician and my 840 Evo doesnt even appear on the drop down list. The software even says Rapid Mode is disabled even though I can see the Rapid Mode service through task manager.
Now Im just running tests, and restarting the laptop to install additional Windows updates. Upgrade to Windows 8.1 actually went through this time. After the update, Magician now says that Rapid Mode is on and my SSD again appears to be selectable. Read speeds seems to have gotten a *tiny bit* better but it is still extremely low.
Decided to say screw it, disabled Rapid Mode, restarted, again with the "Start PXE over IPv6/4". Turn off laptop, turn on, surprisingly no BSOD saying my system is forever broken. Now Im trying to see if I could salvage the performance back through messing with the settings so I followed most of the advice on another website.
Now it seems that the write speed is consistently good, but again the read speeds are absolutely horrid. I used AS-SSD for the benchmark instead of CrystalDiskMark this time.
And that is where I am right now. I am very sorry that the post is ridiculously long. I've been constantly looking around the internets to see if anyone has the same problem as me and I couldnt find a solution. I wanted to somewhat be detailed with my process so I can know whether this problem is the software or the MSI hardware. Or if the problem is with my specific SSD and that I'd have to RMA it.

Answer 1

How did you go about installing Windows?
It looks like the first time you used some software that ended up cloning it from the HDD to the SSD. That's a no-no in general, and I'd never trust it to work well.
Then the next time, you say you restored it. But you don't say if that was from the SSD/HDD or from recovery media that you had generated.
I'll be perfectly honest, I'd only trust installing from Recovery media when it comes to installing a new drive.
I'd say to do that. Install from Recovery media and see if that fixes the problem.
I will also say that a number of users have had issues with the Samsung 840 drives. Most of them were using the Samsung 840 Pro drives, not the EVO's, but just something to keep in mind. They were only able to get them to operate at SATA2 speeds.