Samsung 850 Pro 256 Gb. 6 Gb/s, AHCI. Why are the speeds so low?

Question

Solid State Drives

Hi all! There is a PROBLEM - help if I do not understand myself!
Briefly:
Samsung 850 Pro 256 Gb.
Only the system.
Magician shows: SATA 6 Gb/s, AHCI, Trim incl.
This connection and BIOS settings correspond.
Briefly on the computer:
Manufacturer ASUSTeK Computer INC.
Model P7H57D-V EVO
Rev 1.xx
Name Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz
Processor socket Socket 1156 LGA
Memory type DDR3
Installed Memory 8192.0 MB
Channels Dual
6121 SATA2 Controller
Vendor Marvell Technology Group Ltd.
Device Subsystem Vendor ASUSTeK Computer Inc
Device Subsystem Name 6121 RAID Controller
Windows Name Standard Dual Channel PCI IDE Controller
Class Name IDE ATA/ATAPI Controllers
Bus Type PCI-X
88SE9123 PCIe SATA 6.0 Gb/s controller
Vendor Marvell Technology Group Ltd.
Device subsystem vendor ASUSTeK Computer Inc
Device subsystem name <unknown>
Windows Name Standard SATA AHCI Controller
Serial ATA class name (AHCI 1.0)
PCI-X bus type
CrystalDiskMark revealed:
CrystalDiskMark 6.0.0 x64 (C) 2007-2017 hiyohiyo
Crystal Dew World : https://crystalmark.info/------------------------------------
_ -----------------------------
* MB/s = 1,000,000 bytes/s [SATA/600 = 600,000,000 bytes/s]
* KB = 1000 bytes, KiB = 1024 bytes
Sequential Read (Q= 32,T= 1) : 328.784 MB/s - WHY IS THE SPEED SMALL?!!!
Sequential Write (Q= 32,T= 1) : 170.006 MB/s - WHY IS THE SPEED SLOW?!!!
Random Read 4KiB (Q= 8,T= 8) : 173.147 MB/s [ 42272.2 IOPS]
Random Write 4KiB (Q= 8,T= 8) : 111.498 MB/s [ 27221.2 IOPS]
Random Read 4KiB (Q= 32, T= 1) : 161.469 MB/s [ 39421.1 IOPS]
Random Write 4KiB (Q= 32,T= 1) : 105.035 MB/s [ 25643.3 IOPS]
Random Read 4KiB (Q= 1,T= 1) : 24.600 MB/ s [ 6005.9 IOPS]
Random Write 4KiB (Q= 1,T= 1) : 49.049 MB/s [ 11974.9 IOPS]
Test : 1024 MiB [C: 27.2% (64.8/238.5 GiB)] (x5) [Interval=5 sec ]
Date : 2018/03/27 18:32:16
OS : Windows 10 Enterprise [10.0 Build 14393] (x64)
And in general, all speeds are low!!!
The 50Mb, 8Gb tests are similar in speed to the 1GB test.
Reading, writing - the built-in program of Windows shows no more than 50 mb / s !!!
Windows loading is fast!
Completion is fast!
BUT values ​​of the resulted tests hover.
Thank you and kudos!
maybe because Marvell Technology Group Ltd. ?

Answer 1

Question
Answer

Only the system.

Answer 2

It's all "SATA2 Controller"