Difference is not groundbreaking. Try to run Crystaldiskmark and post result here.
ok I did this but I don't know what I'm looking at so here is the "Copy" from Crystal: minus the blah blah zero's. The 1tb drive is the one I am only getting 3gb/s according to the samsung proggy.
Robert
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CrystalDiskInfo 7.0.5 (C) 2008-2016 hiyohiyo
Crystal Dew World :
http://crystalmark.info/
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OS : Windows 10 [10.0 Build 15063] (x64)
Date : 2017/06/03 10:13:46
-- Controller Map ----------------------------------------------------------
+ Standard SATA AHCI Controller [ATA]
- Samsung SSD 840 PRO Series
-
- Samsung SSD 850 PRO 1TB
- Microsoft Storage Spaces Controller [SCSI]
-- Disk List ---------------------------------------------------------------
(1) Samsung SSD 840 PRO Series : 512.1 GB [0/0/0, pd1] - sg
(2) Samsung SSD 850 PRO 1TB : 1024.2 GB [2/0/0, pd1] - sg
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(1) Samsung SSD 840 PRO Series
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Model : Samsung SSD 840 PRO Series
Firmware : DXM06B0Q
Serial Number : S1AXNSAFA04099K
Disk Size : 512.1 GB (8.4/137.4/512.1/512.1)
Buffer Size : Unknown
Queue Depth : 32
# of Sectors : 1000215216
Rotation Rate : ---- (SSD)
Interface : Serial ATA
Major Version : ACS-2
Minor Version : ATA8-ACS version 4c
Transfer Mode : SATA/600 | SATA/600
Power On Hours : 10923 hours
Power On Count : 2294 count
Host Writes : 29282 GB
Wear Level Count : 77
Temperature : 32 C (89 F)
Health Status : Good (100 %)
Features : S.M.A.R.T., 48bit LBA, NCQ, TRIM
APM Level : ----
AAM Level : ----
Drive Letter : C:
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(2) Samsung SSD 850 PRO 1TB
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Model : Samsung SSD 850 PRO 1TB
Firmware : EXM04B6Q
Serial Number : S252NXAG715017W
Disk Size : 1024.2 GB (8.4/137.4/1024.2/1024.2)
Buffer Size : Unknown
Queue Depth : 32
# of Sectors : 2000409264
Rotation Rate : ---- (SSD)
Interface : Serial ATA
Major Version : ACS-2
Minor Version : ATA8-ACS version 4c
Transfer Mode : SATA/300 | SATA/600
Power On Hours : 8505 hours
Power On Count : 1625 count
Host Writes : 17139 GB
Wear Level Count : 20
Temperature : 28 C (82 F)
Health Status : Good (100 %)
Features : S.M.A.R.T., 48bit LBA, NCQ, TRIM, DevSleep
APM Level : ----
AAM Level : ----
Drive Letter : D: