Aside from troubleshooting, you should install Samsung Magician if you haven't done so and:
1) Update the SSD firmware
2) Set profile to Max speed
3) Overprovision (not necessary but recommended)
4) run "Performance Optimization"
5) Run the BENCHMARK
6) do NOT. I repeat, do NOT use Rapid Mode at least until we figure out the problem.
Now you do appear to have a problem, I just prefer the Samsung Magician benchmark.
After you've done the above->
a) Install the "MAIN CHIPSET" and any relevent SATA drivers direct from the Motherboard support site if you haven't done so.
b) Make sure you are using the BEST SATA controller which should be the INTEL one in your case likely (see motherboard manual)
*I'm confused what you mean by it being SLOWER using Intel's but now using Windows' driver. I'm not sure how you SWITCHED them.
I believe it's either a DRIVER issue, or something a BIOS update would fix.
You appear to only have the Intel SATA controller. It's a good one and should give nearly identical performance to mine. The ONLY thing I can currently think of would be if you didn't install the MAIN CHIPSET driver called "Intel INF Installation" probably and you shouldn't be changing the driver used.
Same problem here. I have a pretty old computer without AHCI, without trim function, SATA II with no controller BUT anyway I didnt compare my two Samsung EVO 1TB performance with other systems performances, but with another SSD I have in my computer, a 60 GB Mushkin Callisto DeLuxe.
I have to mention I applyed your advices in that order you mentioned for the Samsung SSDs.
1. CrystalDiskMark 3.0.3 x64
For Samsung EVO 1 TB....................................For Mushkin Callisto DeLuxe 60GB
READ (MB/s)...WRITE (MB/s)..............................READ (MB/s)...WRITE (MB/s)
I figured out, that my ssd become slow only if I connect my WD 1TB Green sata HDD to my mobo.
If I unplug it the ssd is lightning fast.
I mean I understand if the hdd slows down the boot time, but why the write/read speed of the ssd are affected?